TSN multi-domain clock synchronization method and system for avionics network

Abstract

The invention discloses a TSN multi-domain clock synchronization method and system oriented to an avionics network, and the method comprises the steps: dividing the avionics network into a main domain and a backup domain, and building a clock synchronization tree of each domain; configuring a role of a port corresponding to each domain according to the clock synchronization tree path of each domain; establishing an RTC updating mechanism of each domain; and performing multi-domain time synchronization message control based on the RTC updating mechanism of each domain. The multi-domain scheme provided by the invention can be implemented only by modifying PTP protocol stack software without modifying a TSN switch chip or hardware, so that the flexibility is relatively high; according to the scheme, the method can be quickly deployed in the avionics network, and the problem of independent time synchronization of multiple domains in the avionics network is solved.

Description

Technical Field

[0001] The present invention discloses a TSN multi-domain clock synchronization method and system for an avionics network, belonging to the technical field of aviation communications. Background Art

[0002] In communication networks, the normal operation of many services (such as wireless base stations and industrial automation control) requires network clock synchronization, or the time or frequency difference between devices in the entire network is kept within a reasonable error level. Time synchronization ensures that the frequency and phase between signals remain consistent, thereby ensuring the stability and reliability of communication.

[0003] The precise time synchronization PTP protocol is used to solve the time synchronization problem in the communication network and can be used for high-precision time synchronization between devices. The PTP protocol establishes a master-slave system between the clocks in the system, and the time of the clocks in the system is derived from the best master clock. The best master clock exchanges PTP messages with the slave clock, and the slave clock calculates the clock deviation and network delay between the master clock and the master clock through the timestamp information carried in the PTP message, thereby achieving synchronization.

[0004] Traditional protocols such as PTP and gPTP only support single-domain configuration, that is, all devices in the network topology are configured in the same clock domain, but new vehicle-mounted and avionics networks need to support multi-domain division, each domain has a separate clock tree, and each domain is independent of each other. The traditional IEEE802.1AS-2011 version of single-domain time synchronization has become increasingly unable to meet actual application needs. In avionics networks, there are multiple different electronic control systems that are independent of each other. In practice, they are often divided into multiple control domains, each with its own independent VLAN, and data services are also isolated. Therefore, clock synchronization should also be independent and separated. Therefore, the gPTP protocol needs to be improved to support multi-domain clock synchronization solutions. Summary of the invention

[0005] In order to solve the problems of algorithms, protocols, management and control under multi-domain clock synchronization, the present invention provides a TSN multi-domain clock synchronization method for avionics networks, which realizes multi-domain clock synchronization by improving multi-domain models and domain division, multi-domain port roles and states, RTC update mechanism, multi-domain clock synchronization message management and control, and multi-domain switching.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: The present invention provides a TSN multi-domain clock synchronization method for an avionics network, comprising: Perform multi-domain division and establish clock synchronization trees for each domain; Configure the role of the corresponding port in each domain according to the clock synchronization tree path of each domain; Establish RTC update mechanism for each domain; Based on the RTC update mechanism of each domain, multi-domain time synchronization message control is performed.

[0007] Preferably, the multi-domain division and establishment of a clock synchronization tree for each domain include: The GM master-slave domain module is used to divide the avionics network into a master domain and a backup domain, and each domain is configured with an independent clock synchronization tree; Different synchronization tree paths are set for different domains based on domain division.

[0008] Preferably, configuring the role of the port corresponding to each domain according to the clock synchronization tree path of each domain also includes: The time synchronization roles of the same port in different domains can be configured differently.

[0009] Preferably, the establishment of the RTC update mechanism for each domain includes: Update the RTC with the time synchronized by the primary domain.

[0010] Preferably, the establishment of the RTC update mechanism for each domain includes: Extract timestamps t1, t2, t3, t4 and correction field values ​​from the time synchronization message obtained from the time synchronization port of the current domain; where t1 is the sending time of the Pdelay_Req message, t2 is the receiving time of the Pdelay_Req message, t3 is the sending time of the Pdelay_Resp message, t4 is the receiving time of the Pdelay_Resp message, and correctionfield is the delay time calculated by the previous hop; Pdelay_Req message and Pdelay_Resp message are messages in the PDelay protocol; The frequency deviation offset is calculated based on the timestamps t1, t2, t3, and t4, and the calculation method is: offset = ( ( t2- t1 ) - ( t4 - t3 ) ) / 2; and the delay delay of the current jump is calculated based on the timestamps t1, t2, t3, and t4; Determine whether the current domain is the main domain. If so, update the RTC of each device in the domain based on the frequency deviation offset; otherwise, do not update. The update method is: use the calculated frequency deviation offset value to write the RTC register of the current device to give frequency compensation to the hardware clock.

[0011] Preferably, the method further comprises: Determine whether the current domain is the primary domain by setting the primary domain flag.

[0012] Preferably, the RTC update mechanism based on each domain performs multi-domain time synchronization message control, including: When sending multi-domain messages, each domain fills in the corresponding domain ID and adds the sending timestamp when encapsulating the message, and then sends it to the time synchronization port; When receiving multi-domain messages, a receiving timestamp is added first. The time synchronization port receives multi-domain messages and caches them in a buffer queue. The polling port obtains the message from the buffer queue, decapsulates it, and identifies the domain ID. Based on the domain ID, the decapsulated message is sent to the corresponding domain message processing engine. The domain message processing engine obtains the timestamp t1, t2, t3, t4 and correction field values ​​from the message, and then calculates the offset and delay values. The RTC of each device in the domain is updated according to the calculated offset value to achieve multi-domain time synchronization.

[0013] Preferably, the method further comprises: When the primary domain fails, domain switching is performed; The primary domain fault judgment method is: If no Sync message or Announce message is received for three consecutive times or within a set time, it is determined that the primary domain is faulty; the Sync message and Announce message are messages in the clock synchronization protocol PTP; If a port link failure is detected, it is judged as a primary domain failure; The domain switching refers to receiving a switching instruction, selecting a backup domain with the smallest calculated offset value to switch to the primary domain and setting a primary domain flag, and using the time synchronization result of the new primary domain to update the RTC of each domain.

[0014] The present invention also provides a TSN multi-domain clock synchronization system for avionics networks, which is used to implement the above-mentioned TSN multi-domain clock synchronization method for avionics networks. The system includes: The domain partitioning module is used to perform multi-domain partitioning and establish the clock synchronization tree of each domain; A configuration module is used to configure the role of the corresponding port in each domain according to the clock synchronization tree path of each domain; Update module, used to establish RTC update mechanism for each domain; The synchronization control module performs multi-domain time synchronization message control based on the RTC update mechanism of each domain.

[0015] Preferably, the system further comprises: The switching module is used to establish a multi-domain switching mechanism. When receiving a switching instruction from the host computer, it performs domain switching and updates the RTC.

[0016] The present invention provides a TSN multi-domain clock synchronization method and system for avionics networks, which has the following beneficial effects: (1) The implementation of the multi-domain solution only requires modifying the PTP protocol stack software implementation, without modifying the TSN switch chip or hardware, which is highly flexible; (2) The multi-domain solution implements the backup of GM and clock synchronization tree, which is more reliable; (3) The multi-domain solution algorithm is simple to implement and is compatible with the single-domain mode. The convergence speed is fast when switching between multiple domains, ensuring the stability of the network. (4) It can be quickly deployed in the avionics network to solve the problem of independent time synchronization of multiple domains in the avionics network. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of multi-domain division and networking provided by an embodiment of the present invention; Figure 2 A schematic diagram of the domain port role configuration provided by an embodiment of the present invention; Figure 3 A schematic diagram of an RTC update process provided by an embodiment of the present invention; Figure 4 A schematic diagram of a multi-domain message sending mechanism provided by an embodiment of the present invention; Figure 5 A schematic diagram of a multi-domain message sending process provided by an embodiment of the present invention; Figure 6 A schematic diagram of a multi-domain message receiving mechanism provided by an embodiment of the present invention; Figure 7 A schematic diagram of a multi-domain message receiving process provided by an embodiment of the present invention; DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0019] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions according to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0020] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components.

[0021] It should also be noted that, unless otherwise specified, the term “connection” herein may refer not only to a direct connection but also to an indirect connection involving an intermediate.

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0023] It should be emphasized here that the step marks mentioned below are not intended to limit the order of the steps, but it should be understood that the steps can be executed in the order mentioned in the embodiment, or in a different order from the embodiment, or several steps can be executed simultaneously.

[0024] The embodiment of the present invention provides a TSN (Time Sensitive Network) multi-domain clock synchronization method for avionics networks, which realizes TSN multi-domain clock synchronization by improving multi-domain models and domain division, multi-domain port role and status configuration, RTC (Real Time Clock) update mechanism, multi-domain clock synchronization message management and control, multi-domain switching, etc. The specific implementation process is as follows: S1. Perform multi-domain division and establish a clock synchronization tree for each domain; S2. According to the clock synchronization tree path of each domain, configure the role of the corresponding port in the domain; S3, establish the RTC update mechanism of each domain; S4, based on the RTC update mechanism of each domain, multi-domain time synchronization message control; S5. Establish a multi-domain switching mechanism. When receiving a switching notification from the host computer, perform domain switching and update RTC.

[0025] In the embodiment of the present invention, multiple domains are divided and a clock synchronization tree of each domain is established. The specific implementation process is as follows: The embodiment of the present invention adopts the GM (Grandmaster) master-slave domain model, in which each domain is independent, has its own independent clock synchronization tree, and has its own independent GM, but the GMs are in a backup relationship with each other. Figure 1 As shown, Figure 1 This is a case of two domains. In fact, more domains can be divided according to application needs.

[0026] Based on the above domain division, different synchronization tree paths can be set for different domains.

[0027] In the embodiment of the present invention, the role of the corresponding port in each domain is configured according to the clock synchronization tree path of each domain. The specific implementation process is as follows: In the aviation field, port roles are generally set statically, and the BMCA algorithm election is not enabled.

[0028] The time synchronization role of the same port in different domains may be different. This can be configured based on the synchronization path tree of the domain. Figure 2 This is a typical configuration solution (two domains). Figure 1 The following figure shows the role configuration of each port in domain 0. The following figure shows the role configuration of each port in domain 1.

[0029] In the embodiment of the present invention, an RTC update mechanism for each domain is established, and the specific implementation process is as follows: When updating the hardware RTC in multiple domains, you need to consider which domain's time synchronization result to update. For the scenario of multi-domain backup GM, use the time synchronized by the primary GM to update the RTC of each domain. The RTC update algorithm is as follows: Figure 3 As shown, specifically including: Get the timestamps t1, t2, t3, t4 and correction field value from the time synchronization message received by the time synchronization port; where t1 is the sending time of the Pdelay_Req message; t2 is the receiving time of the Pdelay_Req message; t3 is the sending time of the Pdelay_Resp message; t4 is the receiving time of the Pdelay_Resp message; correctionfield is the forwarding delay delay time calculated by the previous hop.

[0030] It should be noted that the Pdelay_Req message and the Pdelay_Resp message are messages in the PDelay protocol. The PDelay protocol is based on the clock synchronization protocol PTP. The Pdelay_Req message is used to trigger the delay measurement between two network devices, and the Pdelay_Resp message is used to return the delay measurement result.

[0031] The frequency deviation offset is calculated based on the timestamps t1, t2, t3, and t4. The calculation formula is as follows: offset = ((t2-t1)-(t4-t3)) / 2, The delay is calculated based on the timestamps t1, t2, t3, and t4. The calculation formula is as follows: delay = ( ( t2 - t1 ) + ( t4 - t3 ) ) / 2, Determine whether the current domain is the primary domain. If so, update the RTC of each device in the domain; otherwise, do not update. The update method is as follows: (1) Determine whether the domain the device is currently in is the primary domain. If so, jump to step 2; otherwise, end directly; (2) Use the calculated offset value to write the RTC register of the current device and apply frequency compensation to the hardware clock to achieve synchronization.

[0032] It should be noted that, in this embodiment, whether the current domain is the primary domain is determined by setting the primary domain flag.

[0033] In the embodiment of the present invention, multi-domain time synchronization message control is performed based on the RTC update mechanism of each domain. The specific implementation process is as follows: In the multi-domain model, each domain instance has independent time synchronization message interaction; a port may join multiple domains and its role in each domain may be different; at the same time, a port may receive time synchronization messages from multiple domains. The port distinguishes entities from different domains based on the domain ID in the time synchronization message.

[0034] For more information about the multi-domain message sending mechanism, see Figure 4 , Figure 4 In the case of two domains, each domain entity has an independent message sending engine, which independently encapsulates messages and sends them to the time synchronization port. The time synchronization port may have to carry the sending of messages from multiple domains.

[0035] For the multi-domain message sending process, see Figure 5 It is basically similar to the single-domain case. The only difference is that the domain IDs filled in for multiple domain packets are different. The main process is: after the preset message sending time is reached, the message is encapsulated and the corresponding domain ID is filled in, and then it is encapsulated into message forwarding information, and a sending timestamp is added to the message, and it is sent through the time synchronization port.

[0036] For more information about the multi-domain message reception mechanism, see Figure 6 , for the case of two domains, each domain entity has an independent message receiving engine, which independently decapsulates the time synchronization message of the corresponding domain. The PTP port may need to receive and cache messages from multiple domains. Therefore, the domain ID of each domain must be identified and processed separately. For the multi-domain message receiving process, see Figure 7 The main process is as follows: after receiving the message, a receiving timestamp is added to the message, the time synchronization port receives the message and caches it in the buffer queue; the polling port obtains the message from the buffer queue, decapsulates it and identifies the domain ID, and sends the decapsulated message to the corresponding domain message processing engine; the domain message processing engine obtains the timestamp t1, t2, t3, t4 and correction field value from the message, and then calculates the offset and delay values, and updates the RTC of each device in the domain according to the calculated offset value, finally achieving the effect of time synchronization.

[0037] In the embodiment of the present invention, a multi-domain switching mechanism is established. When receiving a switching notification from the host computer, the domain is switched and the RTC is updated. The specific implementation process is as follows: For the backup domain GM scenario, there is a distinction between the primary domain and the backup domain. In this embodiment, when the primary domain fails, it can quickly switch to the backup domain, and the backup domain takes over as the new primary domain. The details are as follows: Determine the primary domain failure: A1. If no Sync or Announce message is received for three consecutive times or within the set time, it is judged as a master domain failure and a fault message is sent to the host computer. It should be noted that the Sync message and the Announce message are messages in the clock synchronization protocol PTP. The Sync message is used by the master clock device to send clock synchronization messages to the slave clock device, and the Announce message sends the characteristic information of its own clock to the outside. A2. If a port link failure is detected, it is determined to be a primary domain failure and a fault message is sent to the host computer.

[0038] Perform domain switching when the primary domain fails: B1. Set the primary domain flag and select the time synchronization result according to the primary domain flag; B2. After receiving the switch notification from the host computer, select the backup domain with the smallest calculated offset value, switch to the primary domain and set the primary domain flag; B3. Use the time synchronization result of the new primary domain to update the RTC of each domain.

[0039] Based on the above invention concept, another embodiment of the present invention further provides a TSN multi-domain clock synchronization system for avionics networks, including: The domain partitioning module is used to perform multi-domain partitioning and establish the clock synchronization tree of each domain; A configuration module is used to configure the role of the corresponding port in each domain according to the clock synchronization tree path of each domain; Update module, used to establish RTC update mechanism for each domain; The synchronization control module performs multi-domain time synchronization message control based on the RTC update mechanism of each domain; The switching module is used to establish a multi-domain switching mechanism. When receiving the switching notification from the host computer, it performs domain switching and updates the RTC.

[0040] This embodiment corresponds to the above method embodiment. The implementation methods of the above method embodiment are all applicable to this embodiment and can achieve the same or similar technical effects, so they will not be described in detail here.

[0041] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0042] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0043] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0044] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A TSN multi-domain clock synchronization method for avionics networks, characterized in that: include: Perform multi-domain division and establish clock synchronization trees for each domain; Configure the role of the corresponding port in each domain according to the clock synchronization tree path of each domain; Establish RTC update mechanism for each domain; Based on the RTC update mechanism of each domain, multi-domain time synchronization message control is performed.

2. A TSN multi-domain clock synchronization method for avionics network according to claim 1, characterized in that: The multi-domain division and establishment of a clock synchronization tree for each domain include: The GM master-slave domain module is used to divide the avionics network into a master domain and a backup domain, and each domain is configured with an independent clock synchronization tree; Different synchronization tree paths are set for different domains based on domain division.

3. The TSN multi-domain clock synchronization method for avionics network according to claim 1, characterized in that: The configuring the role of the port corresponding to each domain according to the clock synchronization tree path of each domain also includes: The time synchronization roles of the same port in different domains can be configured differently.

4. A TSN multi-domain clock synchronization method for avionics networks according to claim 2, characterized in that: The RTC update mechanism for each domain is established, including: Update the RTC with the time synchronized by the primary domain.

5. A TSN multi-domain clock synchronization method for avionics network according to claim 4, characterized in that: The RTC update mechanism for each domain is established, including: Extract timestamps t1, t2, t3, t4 and correction field values ​​from the time synchronization message obtained from the time synchronization port of the current domain; where t1 is the sending time of the Pdelay_Req message, t2 is the receiving time of the Pdelay_Req message, t3 is the sending time of the Pdelay_Resp message, t4 is the receiving time of the Pdelay_Resp message, and correctionfield is the delay time calculated by the previous hop; Pdelay_Req message and Pdelay_Resp message are messages in the PDelay protocol; The frequency deviation offset is calculated based on the timestamps t1, t2, t3, and t4. The calculation method is: offset = ((t2-t1)-(t4-t3)) / 2; and the delay of the current jump is calculated based on the timestamps t1, t2, t3, and t4. Determine whether the current domain is the main domain. If so, update the RTC of each device in the domain based on the frequency deviation offset; otherwise, do not update. The update method is: use the calculated frequency deviation offset value to write the RTC register of the current device to give frequency compensation to the hardware clock.

6. A TSN multi-domain clock synchronization method for avionics network according to claim 5, characterized in that: The method further comprises: Determine whether the current domain is the primary domain by setting the primary domain flag.

7. The TSN multi-domain clock synchronization method for avionics network according to claim 5, characterized in that: The RTC update mechanism based on each domain performs multi-domain time synchronization message control, including: When sending multi-domain messages, each domain fills in the corresponding domain ID and adds the sending timestamp when encapsulating the message, and then sends it to the time synchronization port; When receiving multi-domain messages, a receiving timestamp is added first. The time synchronization port receives multi-domain messages and caches them in a buffer queue. The polling port obtains the message from the buffer queue, decapsulates it, and identifies the domain ID. Based on the domain ID, the decapsulated message is sent to the corresponding domain message processing engine. The domain message processing engine obtains the timestamps t1, t2, t3, t4 and correctionfield values ​​from the message, and then calculates the offset and delay values. The RTC of each device in the domain is updated according to the calculated offset value to achieve multi-domain time synchronization.

8. A TSN multi-domain clock synchronization method for avionics networks according to claim 7, characterized in that: The method further comprises: When the primary domain fails, domain switching is performed; The primary domain fault judgment method is: If no Sync message or Announce message is received for three consecutive times or within a set time, it is determined that the primary domain is faulty; the Sync message and Announce message are messages in the clock synchronization protocol PTP; If a port link failure is detected, it is judged as a primary domain failure; The domain switching refers to receiving a switching instruction, selecting a backup domain with the smallest calculated offset value to switch to the primary domain and setting a primary domain flag, and using the time synchronization result of the new primary domain to update the RTC of each domain.

9. A TSN multi-domain clock synchronization system for avionics networks, characterized in that: The system for implementing the TSN multi-domain clock synchronization method for avionics networks according to any one of claims 1 to 8 comprises: The domain partitioning module is used to perform multi-domain partitioning and establish the clock synchronization tree of each domain; A configuration module is used to configure the role of the corresponding port in each domain according to the clock synchronization tree path of each domain; Update module, used to establish RTC update mechanism for each domain; The synchronization control module performs multi-domain time synchronization message control based on the RTC update mechanism of each domain.

10. The TSN multi-domain clock synchronization system for avionics network according to claim 9, characterized in that: The system further comprises: The switching module is used to establish a multi-domain switching mechanism. When receiving a switching instruction from the host computer, it performs domain switching and updates the RTC.

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