Fca-ae-1553 redundant network transmission management method

Abstract

This invention belongs to the field of high-speed optical fiber communication technology and provides a method for transmission management in an FC-AE-1553 redundant network. The method includes: a first network node receiving data from an upper-layer application through a transmit buffer, dividing the data into multiple small data blocks and buffering them, managing the small data blocks by transmit management and assembling them into protocol frames, and transmitting the protocol frames through a transmit channel; a second network node receiving the protocol frames through a receive channel, buffering the protocol frames in a receive buffer, processing the protocol frames in the receive buffer based on a receive management table set for the first network node, and submitting corresponding content to the upper-layer application according to the processing results. The beneficial effects of this invention are that it solves problems such as protocol frame loss, out-of-order delivery, and duplication under FC-AE-1553 redundant network structure conditions; and it solves the protocol frame management problem under conditions of multiple switching, multiple sequences, and long sequences when transmitting large amounts of data in an FC-AE-1553 redundant network structure.

Description

Technical Field

[0001] This invention relates to high-speed optical fiber communication technology, and more specifically, to a method for managing redundant network transmission in FC-AE-1553. Background Technology

[0002] The FC-AE-1553 (Fibre Channel Avionics Environment) protocol is a high-speed fiber optic communication technology used in integrated electronic information systems for aviation and aerospace.

[0003] The main components of an FC-AE-1553 network include a network controller (NC), network terminals (NT), and FC-AE switches. The NC and NT can be collectively referred to as FC-AE-1553 network nodes.

[0004] The NC is the node that issues commands in the FC-AE-1553 network. Every data exchange in the FC-AE-1553 network begins with the NC initiating a data transmission command.

[0005] The NT responds to commands issued by the NC in the FC-AE-1553 network and performs corresponding data transmission and reception based on the commands initiated by the NC.

[0006] The FC-AE-1553 protocol frames are divided into three types: command frames, data frames, and status frames. The header format is the same for all three types of frames, such as... Figure 1 As shown. Here, R_CTL represents the protocol frame type, using different values ​​to represent command frames, data frames, and status frames; S_ID represents the source address; D_ID represents the destination address; CS_CTL represents the protocol frame priority; TYPE represents the service type; F_CTL represents frame control related information; SEQ_ID represents the sequence number of the protocol frame; DF_CTL represents the optional frame header; SEQ_CNT represents the count in a specific sequence of this protocol frame; OX_ID represents the exchange sequence number of the protocol frame; RX_ID represents the sequence number of the received exchange response; and the Parameter Field is a reserved parameter field.

[0007] In many systems, for redundancy, multiple Network Controllers (NCs) are configured simultaneously, with each NC acting as a backup for the others. Each NC is connected to all Network Providers (NTs). Multiple switches are also used to connect each NC to all NTs, creating multiple paths between each NC and all NTs. In this setup, the same protocol frame will generate multiple copies and be transmitted through different paths to achieve system redundancy. For example... Figure 2The diagram shows two NCs existing simultaneously, with each NC interconnected with the NT via two FC-AE switches. Figure 2 There are four different paths from the data source to each NT. A protocol frame sent by the data source may have four copies reaching the NT.

[0008] In this redundant network structure, NT will receive a large number of duplicate protocol frames or protocol frames in out of order, which can lead to data reception errors if not handled properly. Summary of the Invention

[0009] This invention aims to provide a redundant network transmission management method for FC-AE-1553 to solve the following technical problems: 1. Solve problems such as protocol frame loss, out-of-order delivery, and duplication under the redundant network structure of FC-AE-1553; 2. Solve the protocol frame management problem under the conditions of multiple switching, multiple sequences, and long sequences when transmitting large amounts of data in the redundant network structure of FC-AE-1553.

[0010] This invention provides a redundant network transmission management method for FC-AE-1553, comprising: The first network node receives data from the upper-layer application through a sending buffer, divides the data into multiple small data blocks and buffers them, and the sending management assembles the small data blocks into a protocol frame, which is then transmitted through the sending pipe. The second network node receives the protocol frames through the receiving pipe, the receiving buffer caches the protocol frames, the receiving management processes the protocol frames in the receiving buffer based on the receiving management table set for the first network node, and submits the corresponding content to the upper layer application according to the processing result.

[0011] Furthermore, the step of dividing the data into multiple small data blocks and buffering them, and then having the transmission management compose the small data blocks into protocol frames, includes: The same exchange sequence number is assigned to each of the small data blocks, and the protocol frames composed of the corresponding small data blocks all use the same exchange sequence number.

[0012] Furthermore, the step of assigning the same exchange sequence number to the small data blocks, and ensuring that all protocol frames composed of the corresponding small data blocks use the same exchange sequence number, includes: If the first network node is receiving data from the upper-layer application for the first time after power-on, then the value of the exchange sequence number is randomly selected. If the first network node is not receiving data from the upper-layer application for the first time after power-on, the sequence number of the transmission buffer is incremented by 1 each time it receives new data from the upper-layer application; the sequence number is repeated from 0 after reaching a set value. If the protocol frame sent by the first network node is a response to the received protocol frame, then the small data block is assigned the same exchange sequence number as the received protocol frame.

[0013] Furthermore, the transmission management composes the small data blocks into protocol frames, which include command frames, data frames, and status frames; the count in a sequence of consecutive command frames, data frames, or status frames with the same exchange sequence number starts from 0, and then increments by 1 according to the number of command frames, data frames, or status frames; after the count in a sequence of command frames, data frames, or status frames reaches a set value, the count is repeated starting from 0.

[0014] Furthermore, the sequence numbers of consecutive command frames, data frames, or status frames with the same exchange sequence number start from 0; when the count in a certain sequence of command frames, data frames, or status frames is repeated once from 0, the sequence number is incremented by 1; after the sequence number of each command frame, data frame, or status frame reaches the set value, it is repeated from 0.

[0015] Furthermore, the receiving management table includes node addresses and a receiving record table: The node address is used to record the source address in the received protocol frame, that is, the address of the first network node; The receiving record table includes the following sub-tables: a receiving exchange sequence number record table, used to record the exchange sequence number of the received protocol frame; a receiving sequence number record table, used to record the continuous value range of the sequence number of the received protocol frame; and a receiving sequence count record table, used to record the continuous value range of the count in a certain sequence of the received protocol frame.

[0016] Furthermore, the receive management processes the protocol frames in the receive buffer based on the receive management table set for the first network node, and submits corresponding content to the upper-layer application according to the processing result, including: The initial value of the sequence number record in the received sequence number record table is set to -1. When the second network node receives the protocol frame for the first time, the sequence number record value is updated to the sequence number of the protocol frame. Upon receiving a new protocol frame, the exchange sequence number of the new protocol frame is compared with the exchange sequence number record value. Based on the comparison result, the new protocol frame is processed, and the corresponding content is submitted to the upper-layer application according to the processing result.

[0017] Furthermore, upon receiving each new protocol frame, the exchange sequence number of the new protocol frame is compared with the exchange sequence number record value. Based on the comparison result, the new protocol frame is processed, and corresponding content is submitted to the upper-layer application according to the processing result, including: When the exchange sequence number of a new protocol frame is equal to the exchange sequence number record value, a sequence number comparison and a count comparison in a certain sequence are performed. If both comparisons are correct, the data payload of all received protocol frames is submitted to the upper layer application. When the exchange sequence number of a new protocol frame is greater than the exchange sequence number record value and the difference is 1, the exchange sequence number record value is updated with the exchange sequence number of the protocol frame; wherein, when the exchange sequence number record value has reached a set value, if the exchange sequence number of the protocol frame in the receive buffer is 0, it is considered that the exchange sequence number of the protocol frame is greater than the exchange sequence number record value and the difference is 1. When the sequence number of a new protocol frame is greater than the recorded sequence number value and the difference exceeds 1, an error is reported to the upper-layer application, resulting in frame loss. If the sequence number of a new protocol frame is smaller than the sequence number record value, the protocol frame is discarded and no further processing is performed.

[0018] Furthermore, the step of comparing sequence numbers when the exchange sequence number of the protocol frame in the receive buffer is equal to the exchange sequence number record value includes: In the received sequence number record table, the sequence number interval record value is initially set to empty. Each time the second network node receives a protocol frame, the sequence number interval record value is updated to the maximum and minimum values ​​of all consecutive value intervals of the sequence number of the protocol frame. When the second network node receives the last protocol frame, and the sequence number interval records only have one maximum and one minimum value, it indicates that the sequence number comparison is correct, and the sequence number interval records are reset to empty. When the second network node receives the last protocol frame, and the sequence number interval records more than one maximum and one minimum value, it indicates that the sequence number of the protocol frame is not continuous, the sequence number comparison is incorrect, and an error is reported to the upper layer application, resulting in protocol frame loss.

[0019] Furthermore, the step of performing a count comparison in a certain sequence when the exchange sequence number of the protocol frame in the receive buffer is equal to the exchange sequence number record value includes: The counting record table in a certain sequence is received. The initial value of the counting interval record in a certain sequence is set to empty. Each time the second network node receives a protocol frame, the value of the counting interval record in a certain sequence is updated to the maximum and minimum values ​​of all consecutive value intervals of the count in a certain sequence of the received protocol frame. When the second network node receives the last protocol frame, and there is only one maximum and one minimum value in the count interval of a certain sequence, it considers the count comparison in a certain sequence to be correct, and resets the count interval record value in a certain sequence to empty. When the second network node receives the last protocol frame, and there is more than one maximum and one minimum value recorded in a certain sequence of count intervals, it indicates that the counts in a certain sequence of the protocol frame are not continuous, the count comparison in a certain sequence is incorrect, and an error is reported to the upper layer application, resulting in the loss of the protocol frame.

[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: This invention addresses issues such as identical data arriving from different paths, out-of-order data arriving from different paths, and data out-of-order due to link interruption by designing a management method for three fields in a protocol frame: the exchange sequence number, the sequence number, and the count in a certain sequence. Compared to existing FC-AE-1553 redundant networks that only use the count in a certain sequence field to manage protocol frames, this invention fully utilizes all three fields to manage protocol frames, more effectively solving problems such as protocol frame loss, out-of-order, and duplication under FC-AE-1553 redundant network structures. It also solves the protocol frame management problem under conditions of multiple exchanges, multiple sequences, and long sequences when transmitting large amounts of data in FC-AE-1553 redundant network structures. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the frame header format of the FC-AE-1553 protocol.

[0022] Figure 2 This is a schematic diagram of the topology of the FC-AE-1553 redundant network.

[0023] Figure 3 A flowchart of the FC-AE-1553 redundant network transmission management method provided in an embodiment of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0026] Example like Figure 3As shown, this embodiment provides a redundant network transmission management method for FC-AE-1553. In this method, each network node, whether NC or NT, performs data transmission through a combination of three parts: a transmission buffer, transmission management, and a transmission pipeline. Similarly, data reception is performed through a combination of three parts: a reception pipeline, a reception buffer, and reception management. This includes: S100, the first network node receives data from the upper layer application through the sending buffer, divides the data into multiple small data blocks and buffers them, the sending management assembles the small data blocks into a protocol frame, and transmits the protocol frame through the sending pipe; S200, the second network node receives the protocol frame through the receiving pipe, the receiving buffer buffers the protocol frame, the receiving management processes the protocol frame in the receiving buffer based on the receiving management table set for the first network node, and submits the corresponding content to the upper layer application according to the processing result.

[0027] The following is a detailed implementation of the FC-AE-1553 redundant network transmission management method described in this embodiment of the invention.

[0028] S100, the first network node, whether NC or NT, receives a certain amount of data from the upper-layer application at a time through a transmission buffer during data transmission. This data is then divided into multiple small data blocks and buffered. The transmission management system assembles these small data blocks into protocol frames, which are then transmitted through the transmission pipeline. This process is repeated continuously to complete the transmission of data of any size. The protocol frame includes command frames, data frames, and status frames. When the send buffer divides data received from the upper-layer application into small data blocks, it assigns the same exchange sequence number OX_ID to each small data block. The same exchange sequence number OX_ID is used when these small data blocks compose command frames, data frames, and status frames. This facilitates the management of various protocol frames composed of data received in a single session. Specific methods for determining the exchange sequence number OX_ID include: If the first network node is receiving data from the upper-layer application for the first time after power-on, then the value of the exchange sequence number OX_ID is randomly selected; If the first network node is not receiving data from the upper-layer application for the first time after power-on, the exchange sequence number OX_ID of the newly received small data block is incremented by 1 each time the transmit buffer receives new data; wherein, in this embodiment, it is preferred that the exchange sequence number OX_ID repeats from 0 after reaching the maximum value; If the protocol frame sent by the first network node is a response to the received protocol frame, then the small data block is assigned the same exchange sequence number OX_ID as the received protocol frame.

[0029] When sending and managing the framing of the small data blocks, this embodiment also requires: For a sequence of command frames, data frames, or status frames with the same exchange sequence number OX_ID, the count SEQ_CNT starts from 0, and then increments by 1 according to the number of command frames, data frames, or status frames in the sequence. After the count SEQ_CNT in a sequence of command frames, data frames, or status frames reaches the maximum value, the count is repeated starting from 0. For consecutive command frames, data frames, or status frames with the same exchange sequence number OX_ID, the sequence number SEQ_ID starts from 0. When the count SEQ_CNT in a certain sequence of the command frame, data frame, or status frame repeats from 0 once, the sequence number SEQ_ID is incremented by 1. After the sequence number SEQ_ID of the command frame, data frame, or status frame reaches the set value, it repeats from 0.

[0030] In this embodiment, each network node, whether NC or NT, performs data reception through three parts: the receiving pipe, the receiving buffer, and the receiving management. In the FC-AE-1553 network, the reception management of each network node will set up an independent reception management table for each other network node; Specifically, the receive management table includes node addresses and a receive record table; the node addresses are used to record the source address S_ID in the received protocol frames, i.e., the address of the first network node, used to distinguish different network nodes; the receive record table specifically includes three sub-tables: The received sequence number record table is used to record the sequence number OX_ID of the received protocol frames; A received sequence number record table is used to record the continuous value range of the sequence number SEQ_ID of the received protocol frames; A count record table is received for a certain sequence, which is used to record the continuous value range of the count SEQ_CNT in a certain sequence of received protocol frames.

[0031] S200, the second network node, whether NC or NT, receives the protocol frames through the receive channel, buffers the protocol frames in the receive buffer, and waits for receive management processing; the second network node's receive management processes the protocol frames in the receive buffer based on the receive management table set for the first network node, and submits the corresponding content to the upper-layer application according to the processing result: In the received sequence number record table, the initial value of the sequence number record is set to -1. When the second network node receives the protocol frame for the first time, the sequence number record value is updated to the sequence number OX_ID of the protocol frame. Subsequently, upon receiving each new protocol frame, the sequence number OX_ID of the new protocol frame is compared with the sequence number record value. Based on the comparison result, the new protocol frame is processed, and the corresponding content is submitted to the upper-layer application according to the processing result. (1) When the exchange sequence number OX_ID of a new protocol frame is equal to the exchange sequence number record value, the sequence number SEQ_ID and the count SEQ_CNT in a certain sequence are compared. If both comparisons are correct, the data payload of all received protocol frames is submitted to the upper layer application: Specifically, the method for comparing the sequence number SEQ_ID and the count SEQ_CNT in a certain sequence is as follows: a) Sequence number SEQ_ID comparison method: In the received sequence number record table, the sequence number interval record value is initially set to empty. Each time the second network node receives a protocol frame, the sequence number interval record value is updated to the maximum and minimum values ​​of all consecutive value intervals of the sequence number SEQ_ID of the protocol frame. When the second network node receives the last protocol frame, and the sequence number interval record value has only one maximum value and one minimum value, that is, the continuous interval of the sequence number of the protocol frame has only one value, it means that the sequence number SEQ_ID comparison is correct, and the sequence number interval record value is reset to empty. When the second network node receives the last protocol frame, and the sequence number interval records more than one maximum and one minimum value, that is, the sequence number interval of the protocol frame is not a single continuous interval, it indicates that the sequence number SEQ_ID of the protocol frame is not continuous, the sequence number SEQ_ID comparison is incorrect, an error is reported to the upper layer application, and a protocol frame is lost.

[0032] b) Comparison method for counting SEQ_CNT in a certain sequence: The count record table in a certain sequence is received. The count interval record value in a certain sequence is initially set to empty. Each time the second network node receives a protocol frame, the count interval record value in a certain sequence is updated to the maximum and minimum values ​​of all continuous value intervals of the count SEQ_CNT in a certain sequence of the received protocol frame. When the second network node receives the last protocol frame, and there is only one maximum and one minimum value recorded in the counting interval of a certain sequence, that is, there is only one continuous value interval of the count in a certain sequence of the protocol frame, then it is considered that the count SEQ_CNT comparison in a certain sequence is correct, and the counting interval recorded in a certain sequence is reset to empty; When the second network node receives the last protocol frame, and there is more than one maximum and one minimum value recorded in a certain sequence of count intervals, that is, there is more than one consecutive value interval for the count in a certain sequence of the protocol frame, it indicates that the count SEQ_CNT in a certain sequence of the protocol frame is not continuous and there is a comparison error of the count SEQ_CNT in a certain sequence. An error is reported to the upper layer application, and a protocol frame is lost.

[0033] (2) When the exchange sequence number OX_ID of the new protocol frame is greater than the exchange sequence number record value and the difference is 1, the exchange sequence number record value is updated with the exchange sequence number of the protocol frame; wherein, when the exchange sequence number record value has reached the set value, if the exchange sequence number of the protocol frame in the receive buffer is 0, it is considered that the exchange sequence number of the protocol frame is greater than the exchange sequence number record value and the difference is 1. (3) When the exchange sequence number OX_ID of the new protocol frame is greater than the exchange sequence number record value and the difference exceeds 1, an error is reported to the upper layer application, resulting in frame loss; (4) If the sequence number OX_ID of the new protocol frame is smaller than the sequence number record value, the protocol frame is discarded and no further processing is performed.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for managing redundant network transmission in an FC-AE-1553 network, characterized in that, include: The first network node receives data from the upper-layer application through a sending buffer, divides the data into multiple small data blocks and buffers them, and the sending management assembles the small data blocks into a protocol frame, which is then transmitted through the sending pipe. The second network node receives the protocol frames through the receiving pipe, the receiving buffer caches the protocol frames, the receiving management processes the protocol frames in the receiving buffer based on the receiving management table set for the first network node, and submits the corresponding content to the upper layer application according to the processing result.

2. The FC-AE-1553 redundant network transmission management method according to claim 1, characterized in that, The step of dividing the data into multiple small data blocks and buffering them, and then having the transmission management system assemble the small data blocks into a protocol frame, includes: The same exchange sequence number is assigned to each of the small data blocks, and the protocol frames composed of the corresponding small data blocks all use the same exchange sequence number.

3. The FC-AE-1553 redundant network transmission management method according to claim 2, characterized in that, Assigning the same exchange sequence number to the small data blocks, and ensuring that all protocol frames composed of the corresponding small data blocks use the same exchange sequence number, includes: If the first network node is receiving data from the upper-layer application for the first time after power-on, then the value of the exchange sequence number is randomly selected. If the first network node is not receiving data from the upper-layer application for the first time after power-on, the sequence number of the transmission buffer is incremented by 1 each time it receives new data from the upper-layer application; the sequence number is repeated from 0 after reaching a set value. If the protocol frame sent by the first network node is a response to the received protocol frame, then the small data block is assigned the same exchange sequence number as the received protocol frame.

4. The FC-AE-1553 redundant network transmission management method according to claim 3, characterized in that, The small data blocks are composed of a protocol frame by the transmission management, and the protocol frame includes a command frame, a data frame, and a status frame; For a sequence of consecutive command frames, data frames, or status frames with the same exchange sequence number, the count starts from 0 and is incremented by 1 according to the number of command frames, data frames, or status frames respectively; after the count in a sequence of command frames, data frames, or status frames reaches the set value, the count is repeated starting from 0.

5. The FC-AE-1553 redundant network transmission management method according to claim 3, characterized in that, The sequence numbers of consecutive command frames, data frames, or status frames with the same exchange sequence number start from 0. When the count in a certain sequence of command frames, data frames, or status frames is repeated once from 0, the sequence number is incremented by 1. After the sequence number of each command frame, data frame, or status frame reaches the set value, it is repeated from 0.

6. The FC-AE-1553 redundant network transmission management method according to claim 1, characterized in that, The receiving management table includes node addresses and a receiving record table: The node address is used to record the source address in the received protocol frame, that is, the address of the first network node; The receiving record table includes the following sub-tables: a receiving exchange sequence number record table, used to record the exchange sequence number of the received protocol frame; a receiving sequence number record table, used to record the continuous value range of the sequence number of the received protocol frame; and a receiving sequence count record table, used to record the continuous value range of the count in a certain sequence of the received protocol frame.

7. The FC-AE-1553 redundant network transmission management method according to claim 6, characterized in that, The receive management process, based on the receive management table set for the first network node, processes the protocol frames in the receive buffer and submits corresponding content to the upper-layer application according to the processing results, including: The initial value of the sequence number record in the received sequence number record table is set to -1. When the second network node receives the protocol frame for the first time, the sequence number record value is updated to the sequence number of the protocol frame. Upon receiving a new protocol frame, the exchange sequence number of the new protocol frame is compared with the exchange sequence number record value. Based on the comparison result, the new protocol frame is processed, and the corresponding content is submitted to the upper-layer application according to the processing result.

8. The FC-AE-1553 redundant network transmission management method according to claim 7, characterized in that, Upon receiving a new protocol frame, the exchange sequence number of the new protocol frame is compared with the exchange sequence number record value. Based on the comparison result, the new protocol frame is processed, and corresponding content is submitted to the upper-layer application according to the processing result, including: When the exchange sequence number of a new protocol frame is equal to the exchange sequence number record value, a sequence number comparison and a count comparison in a certain sequence are performed. If both comparisons are correct, the data payload of all received protocol frames is submitted to the upper layer application. When the exchange sequence number of a new protocol frame is greater than the exchange sequence number record value and the difference is 1, the exchange sequence number record value is updated with the exchange sequence number of the protocol frame; wherein, when the exchange sequence number record value has reached a set value, if the exchange sequence number of the protocol frame in the receive buffer is 0, it is considered that the exchange sequence number of the protocol frame is greater than the exchange sequence number record value and the difference is 1. When the sequence number of a new protocol frame is greater than the recorded sequence number value and the difference exceeds 1, an error is reported to the upper-layer application, resulting in frame loss. If the sequence number of a new protocol frame is smaller than the sequence number record value, the protocol frame is discarded and no further processing is performed.

9. The FC-AE-1553 redundant network transmission management method according to claim 8, characterized in that, When the sequence number of the protocol frame in the receive buffer is equal to the sequence number record value, the sequence number comparison is performed, including: In the received sequence number record table, the sequence number interval record value is initially set to empty. Each time the second network node receives a protocol frame, the sequence number interval record value is updated to the maximum and minimum values ​​of all consecutive value intervals of the sequence number of the protocol frame. When the second network node receives the last protocol frame, and the sequence number interval records only have one maximum and one minimum value, it indicates that the sequence number comparison is correct, and the sequence number interval records are reset to empty. When the second network node receives the last protocol frame, and the sequence number interval records more than one maximum and one minimum value, it indicates that the sequence number of the protocol frame is not continuous, the sequence number comparison is incorrect, and an error is reported to the upper layer application, resulting in protocol frame loss.

10. The FC-AE-1553 redundant network transmission management method according to claim 8, characterized in that, When the sequence number of the protocol frame in the receive buffer is equal to the sequence number record value, the counting comparison in a certain sequence is performed, including: The counting record table in a certain sequence is received. The initial value of the counting interval record in a certain sequence is set to empty. Each time the second network node receives a protocol frame, the value of the counting interval record in a certain sequence is updated to the maximum and minimum values ​​of all consecutive value intervals of the count in a certain sequence of the received protocol frame. When the second network node receives the last protocol frame, and there is only one maximum and one minimum value in the count interval of a certain sequence, it considers the count comparison in a certain sequence to be correct, and resets the count interval record value in a certain sequence to empty. When the second network node receives the last protocol frame, and there is more than one maximum and one minimum value recorded in a certain sequence of count intervals, it indicates that the counts in a certain sequence of the protocol frame are not continuous, the count comparison in a certain sequence is incorrect, and an error is reported to the upper layer application, resulting in the loss of the protocol frame.

Images