An access control method and system of an industrial internet server

Abstract

The application relates to an access control method and system of an industrial internet server. The method comprises the following steps: analyzing a plurality of round-trip delays and a plurality of response delays to obtain a failure coefficient of a target device executing an instruction; determining an execution delay index according to the deviation between the response time length of each process variable of the target device to a plurality of instructions in the same time window and the corresponding preset time length and the failure coefficient; determining an influence index of delayed instruction execution on a process variable according to the correlation between the execution delay indexes of a plurality of time windows and the characteristic values of a plurality of process variables; calculating a risk coupling coefficient corresponding to an instruction sequence according to the delay difference of each adjacent instruction in the instruction sequence; and adjusting the number of access instructions of the server according to the influence index and the risk coupling coefficient. The method can effectively inhibit the chain amplification risk of instruction delay and process variable fluctuation, and guarantee the stability and reliability of the industrial internet access control system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electric communication technology, in particular to an access control method and system of an industrial internet server. BACKGROUND

[0002] In the industrial internet environment, the server usually needs to provide services to both the internal LAN users and the external remote access users. Since the industrial control network often involves key facilities such as SCADA system (Supervisory Control And Data Acquisition), PLC controller (Programmable Logic Controller), DCS system (Distributed Control System), etc., once the access control mechanism has a vulnerability, there may be risks of unauthorized access to perform malicious operations, steal confidential data, etc., and even cause the industrial production line to stop production.

[0003] The access control strategy of the existing method is mostly manually preset, and lacks dynamic adjustment capability, and cannot automatically optimize the strategy according to the real-time network state, device running state or access behavior changes. For example, when the device running state is abnormal, the system cannot automatically tighten the access permission or switch to a more strict access mode. And most of the existing systems are based on pre-strategy matching, lack real-time access behavior analysis and prediction capability, and cannot use machine learning or big data analysis technology to identify potential abnormal access trends in advance. SUMMARY

[0004] In order to solve the above technical problems, the purpose of the present application is to provide an access control method and system of an industrial internet server, and the technical solution adopted is as follows:

[0005] On the one hand, an access control method of an industrial internet server is provided, and the method comprises:

[0006] A plurality of round-trip delays and a plurality of response delays are analyzed to obtain a failure coefficient of a target device executing an instruction; the round-trip delay indicates the time length from sending a test data packet from the server to the target device to receiving its response data packet, and the response delay indicates the time length from sending an instruction from the server to the target device to receiving its corresponding service confirmation response;

[0007] According to the deviation between the response time length of each process variable of the target device to a plurality of instructions within the same time window and the corresponding preset time length, and the failure coefficient, an execution delay index is determined;

[0008] determine an influence index of the instruction delay execution on the process variable according to a correlation between the plurality of execution delay indexes of the plurality of time windows and the characteristic values of the plurality of process variables;

[0009] calculate a risk coupling coefficient corresponding to the instruction sequence according to a delay difference between each adjacent instruction in the instruction sequence; the delay of each instruction is obtained by calculating a deviation between a response duration of the plurality of process variables to the same instruction and a corresponding preset duration; the instruction sequence comprises a plurality of instructions in the plurality of time windows;

[0010] adjust the number of access instructions of the server according to the influence index and the risk coupling coefficient.

[0011] Optionally, the analyzing the plurality of round-trip delays and the plurality of response delays comprises:

[0012] collecting the plurality of round-trip delays and the plurality of response delays in the same time window;

[0013] establishing a coordinate system with a plurality of collection time points in the time window as the horizontal axis and the plurality of round-trip delays as the vertical axis, and performing linear interpolation on each data point in the coordinate system to obtain a round-trip delay broken line, and calculating a slope value between all adjacent data points in the round-trip delay broken line; the plurality of collection time points and the plurality of round-trip delays correspond to each other;

[0014] determining a link degradation index according to a range value of the round-trip delays in the time window and an absolute difference value between each adjacent slope value;

[0015] analyzing the link degradation index and the plurality of response delays to obtain a failure coefficient of the target device executing the instruction.

[0016] Optionally, the analyzing the link degradation index and the plurality of response delays to obtain the failure coefficient of the target device executing the instruction comprises:

[0017] obtaining a sending time point of the server sending the instruction to the target device each time, a response delay of the instruction, and identification information of the instruction in the same time window;

[0018] for each instruction, in response to retrieving a corresponding service confirmation response in the same time window according to the identification information of the instruction, determining a duration between the sending time point of the instruction and the corresponding service confirmation response as a target response delay;

[0019] determining the failure coefficient according to a standard deviation of the plurality of target response delays, a mean value of the plurality of target response delays, and the link degradation index.

[0020] Optionally, the deviation between the response duration of each process variable of the target device to a plurality of instructions within a same time window and the corresponding preset duration, the failure coefficient, are used to determine an execution delay index, which comprises:

[0021] For each process variable, a mean value of the response duration of each process variable to a plurality of instructions within a same time window is calculated to obtain a response duration mean value of each process variable, and a mean value of a plurality of preset durations of each process variable to a plurality of instructions is calculated to obtain a preset duration mean value of each process variable; each instruction corresponds to a preset duration for each process variable regulated by the instruction; the response duration indicates the time duration required for a plurality of process variables of the target device to change from an initial state to a target state after the target device receives each instruction;

[0022] A difference between the response duration mean value of each process variable and the corresponding preset duration mean value is calculated to obtain a response duration difference value;

[0023] An execution delay index is determined according to a plurality of response duration difference values within each time window and the failure coefficient; the plurality of response duration difference values correspond to the plurality of process variables one by one.

[0024] Optionally, the correlation between a plurality of execution delay indexes of a plurality of time windows and a plurality of change characteristic values of a plurality of process variables is used to determine an influence index of instruction delayed execution on process variables, which comprises:

[0025] A coordinate system is established with the time sequence of the plurality of time windows as the horizontal axis and the plurality of execution delay indexes corresponding to the plurality of time windows as the vertical axis, polynomial curve fitting is performed on each data point in the coordinate system, and the vertical coordinates are normalized to obtain an execution curve;

[0026] An independent coordinate system is established for each process variable, with the time sequence number of the plurality of time windows as the horizontal coordinate and the variance value of a plurality of sampling values of the process variable within each time window as the vertical coordinate, polynomial curve fitting is performed on each data point in the coordinate system, and the vertical coordinates are normalized to obtain each change characteristic curve corresponding to each process variable; the plurality of sampling values of each process variable correspond to each time window.

[0027] The mean square errors between the plurality of change characteristic curves and the execution delay index curve are calculated respectively, and the obtained mean square errors are averaged to obtain the influence index of instruction delayed execution on process variables; the plurality of process variables correspond to the plurality of change characteristic curves one by one.

[0028] Optionally, the risk coupling coefficient corresponding to the instruction sequence is calculated according to the delay difference between each adjacent instruction in the instruction sequence, which comprises:

[0029] a difference between a mean value of a response duration of the process variables regulated by each instruction and a mean value of a preset duration corresponding to the process variables regulated by each instruction, to obtain a delay coefficient of each instruction;

[0030] a risk coupling coefficient corresponding to the instruction sequence is calculated according to a difference between the delay coefficients of each adjacent instruction in the instruction sequence.

[0031] Optionally, the risk coupling coefficient corresponding to the instruction sequence is calculated according to a difference between the delay coefficients of each adjacent instruction in the instruction sequence, including:

[0032] a ratio of the delay coefficients of adjacent instructions is calculated according to a ratio of the delay coefficients of a target instruction and a previous instruction of the target instruction; the target instruction is any instruction in the instruction sequence;

[0033] a risk coupling coefficient corresponding to the instruction sequence is determined according to a mean value of the ratios of the delay coefficients of all adjacent instructions in the instruction sequence.

[0034] Optionally, the number of access instructions of the server is adjusted according to the influence index and the risk coupling coefficient, including:

[0035] an access adjustment coefficient of the server is obtained according to a product of the influence index and the risk coupling coefficient;

[0036] the number of access instructions of the server is adjusted according to the access adjustment coefficient of the server.

[0037] Optionally, the number of access instructions of the server is adjusted according to the access adjustment coefficient of the server, including:

[0038] a batch adjustment value is obtained according to a sum of a preset value and the access adjustment coefficient;

[0039] the number of access instructions of the server is adjusted according to a product of an absolute difference between a first threshold value and a second threshold value and the batch adjustment value, and the second threshold value; the first threshold value indicates a preset maximum batch instruction number of the server, and the second threshold value indicates a preset minimum batch instruction number of the server.

[0040] In a second aspect, an access control system of an industrial internet server is provided, and the system includes:

[0041] an analysis module configured to analyze a plurality of round-trip time delays and a plurality of response time delays to obtain a failure coefficient of an instruction executed by a target device; the round-trip time delay indicates a duration from sending a test data packet from a server to the target device to receiving a response data packet, and the response time delay indicates a duration from sending an instruction from the server to the target device to receiving a corresponding service confirmation;

[0042] a first determining module, configured to determine an execution delay index according to a deviation between a response duration of each process variable of the target device to a plurality of instructions in a same time window and a corresponding preset duration, and the failure coefficient;

[0043] a second determining module, configured to determine an influence index of delayed instruction execution on the process variable according to a correlation between a plurality of execution delay indexes of a plurality of time windows and a change characteristic value of the plurality of process variables;

[0044] a calculating module, configured to calculate a risk coupling coefficient corresponding to an instruction sequence according to a delay difference between each adjacent instruction in the instruction sequence; the delay of each instruction is obtained by calculating a deviation between a response duration of the plurality of process variables to a same instruction and a corresponding preset duration; the instruction sequence comprises a plurality of instructions in a plurality of time windows;

[0045] an adjusting module, configured to adjust a number of access instructions of the server according to the influence index and the risk coupling coefficient.

[0046] On the basis of common general knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily, that is, each preferred example of the present application is obtained.

[0047] The present application has the following beneficial effects: the failure coefficient is calculated by comprehensively considering the stability of round-trip delay and the distribution characteristics of response delay, and the risk of instruction out-of-order or retransmission caused by network link instantaneous instability is quantified; the execution delay index is obtained by comparing the deviation between the response duration of each process variable to a plurality of instructions and the theoretical value, and then superimposing the failure coefficient, which directly reflects the execution lag degree of the target device; the influence index is generated by statistically analyzing the correlation between the execution delay indexes of a plurality of time windows and the change characteristic values of the process variables, which is used to measure the amplification effect of instruction delay on process fluctuation; the risk coupling coefficient is obtained by calculating the delay difference between adjacent instructions along the instruction sequence, which describes the chain amplification trend of delay among multiple instructions; the number of access instructions of the server is adjusted according to the influence index and the risk coupling coefficient, which effectively suppresses the chain amplification risk of instruction delay and process variable fluctuation, and guarantees the stability and reliability of the industrial internet access control system. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art and the advantages thereof, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0049] Figure 1 is a flowchart of an access control method of an industrial internet server in one embodiment;

[0050] Figure 2 A schematic structural diagram of an access control system of an industrial internet server in one embodiment;

[0051] Figure 3 A schematic structural diagram of an electronic device in one embodiment. DETAILED DESCRIPTION

[0052] In order to further clarify the technical means and effects taken by the present application to achieve the predetermined purposes, the specific embodiments, structures, features and effects of the access control method and system of an industrial internet server according to the present application are described in detail below in combination with the drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0054] The specific scheme of the access control method of an industrial internet server provided by the present application is described in detail below in combination with the drawings. As shown in Figure 1 The method comprises the following steps:

[0055] S11, analyzing a plurality of round trip delays and a plurality of response delays to obtain a failure coefficient of the target device executing instructions.

[0056] The round trip delay indicates the time length from the server sending a test data packet to the target device to receiving the response data packet thereof. The test data packet is usually a link probe frame (such as 0 byte TCP ACK, UDP Ping or custom heartbeat frame) without business load, which is used to measure the link quality. After the target device receives the test packet, it returns a response data packet immediately at the network protocol stack level, and the response data packet does not contain business processing content.

[0057] The response delay indicates the time length from the server sending an instruction to the target device to receiving the corresponding business confirmation response thereof. The instruction is sent in the form of an instruction message (such as Modbus / TCP function code 03 / 06, OPC UA call or custom control frame), carrying specific control parameters. The target device needs to perform the process action required by the instruction. After the process variable of the target device reaches the target state, a business confirmation response (containing execution result or status word) is returned.

[0058] The server can include an edge computing gateway, a SCADA server (Supervisory Control And Data Acquisition Server), a MES server (Manufacturing Execution System Server), an ERP server (Enterprise Resource Planning Server), a cloud-side industrial PaaS node (Cloud-side Industrial Platform as a Service Node), a virtualized industrial control server, an industrial security management center server, and the like.

[0059] The target device can include a frequency converter, a servo driver, an industrial robot controller, an intelligent sensor, an intelligent meter, an actuator, a valve positioner, a compressor controller, a photovoltaic inverter, a digital twin terminal, an edge industrial gateway, and the like.

[0060] The external operation terminal or management platform initiates an access request to the industrial internet server through a TLS or IPsec encrypted channel, the industrial internet server verifies the permission, and then sends a command message to the target device through an industrial Ethernet, 5G or fieldbus, the target device returns a service confirmation response after execution, and the response is returned to the operation terminal along the original path, thereby forming a complete bidirectional access link.

[0061] When the external operation terminal or management platform initiates an access request, the access control module of the server (industrial internet server) needs to collect data related to the access request in real time, including request source information (source IP address, port number, etc.), terminal attribute information (such as device type, operating system version, etc.), user identity information (such as user ID, authentication method, etc.), and through real-time monitoring of the current network link bandwidth occupation, data packet loss, round-trip delay, link jitter and other data, the network quality of the current regional communication is obtained.

[0062] In real-time collection, the server calls the historical behavior records related to the access request, including the last login time, operation type, operation result and historical alarm information. During the collection process, encryption transmission (such as TLS (Transport Layer Security), Ipsec (Internet Protocol Security)) and data integrity check (such as HMAC (Hash-based Message Authentication Code), CRC (Cyclic Redundancy Check)) methods should be used to ensure the confidentiality and tamper-proofing ability of the collected data during cross-network transmission. And the key collection data is time-stamped and signed to ensure the traceability and timeliness of the data.

[0063] In order to analyze the link round-trip delay trend between the server and the target device (target industrial device) during the access request through the industrial internet server, so as to better identify the instruction inconsistency problem caused by network delay fluctuation, and provide data support for subsequent dynamic adjustment of access control strategy, in one embodiment, a plurality of round-trip delays and a plurality of response delays are analyzed to obtain the failure coefficient of the target device executing instructions, including:

[0064] Collecting a plurality of round-trip delays and a plurality of response delays within the same time window;

[0065] Establishing a coordinate system with the plurality of collection time points in the time window as the horizontal axis and the plurality of round-trip delays as the vertical axis, and performing linear interpolation on each data point in the coordinate system to obtain a round-trip delay broken line, and calculating the slope value between all adjacent data points in the round-trip delay broken line; the plurality of collection time points and the plurality of round-trip delays correspond one by one;

[0066] According to the range value of the round-trip delay in the time window, the absolute difference value between each adjacent slope value, the link degradation index is determined;

[0067] Analyzing the link degradation index and the plurality of response delays to obtain the failure coefficient of the target device executing instructions.

[0068] For the round-trip delay (link round-trip delay), a plurality of measurements are required in the access control process, a time window can be set, which can be 5 min. A plurality of round-trip delays in the time window are collected, a coordinate system is established with a plurality of collection time points in the time window as the horizontal axis and a plurality of round-trip delays corresponding to the plurality of collection time points as the vertical axis, and linear interpolation is performed on each data point in the coordinate system to obtain a round-trip delay broken line. In the round-trip delay broken line, a slope value between two adjacent data points is obtained, denoted as K, and the slope values between all adjacent data points in the round-trip delay broken line are calculated. According to the maximum range of the round-trip delay in the time window and the absolute difference between each adjacent slope value, a link degradation index is determined, and the calculation formula of the link degradation index is:

[0069]

[0070] wherein, is the link degradation index, is the number of groups of slope values in the round-trip delay broken line, is the first group of adjacent data points in the round-trip delay broken line, is the range value of the round-trip delay in the round-trip delay broken line, that is, the difference between the maximum round-trip delay and the minimum round-trip delay in the plurality of round-trip delays in the time window, is the slope value between the first group of adjacent data points in the round-trip delay broken line, is the slope value between the first group of adjacent data points in the round-trip delay broken line. The greater the value of the link degradation index, the more complex the fluctuation of the round-trip delay in the process of sending the access request from the server to the target device.

[0071] The fluctuation of the round-trip delay can be used to measure the stability of the network delay at the link level, but even if the round-trip delay fluctuation is not large, if there is frequent packet loss or retransmission, it will also cause the reliability of instruction execution to decrease. Therefore, in an embodiment, the link degradation index and a plurality of response delays are analyzed to obtain a failure coefficient of the target device executing instructions, including:

[0072] The time when the server sends an instruction to the target device each time in the same time window, the response delay of the instruction, and the identification information of the instruction are obtained.

[0073] For each instruction, the time length between the sending time of the instruction and the corresponding service confirmation response in the same time window is determined as the target response delay in response to the retrieval of the corresponding service confirmation response in the same time window according to the identification information of the instruction.

[0074] ​​The failure coefficient is determined according to the standard deviation of the multiple target response delays, the mean of the multiple target response delays, and the link degradation index.

[0075] The time window is the same as the time window for collecting the multiple round-trip delays and the multiple response delays. The difference between the time when the corresponding service confirmation response is received and the time when the instruction is sent is the response delay of the instruction. The identification information (such as a connection ID, a message ID, or a sequence number) of each instruction is obtained. For each instruction, the corresponding service confirmation response of the instruction in the time window is searched for by using the message ID or the sequence number. If the corresponding service confirmation response of the instruction is received in the time window, the length of time between the time when the corresponding service confirmation response is received and the time when the instruction is sent is confirmed as the target response delay. If the corresponding service confirmation response is not received in the time window, it is determined that there is a timeout or a packet loss, and the response delay is not calculated. The failure coefficient is determined according to the standard deviation of the multiple target response delays, the mean of the multiple target response delays, and the link degradation index. The calculation formula of the failure coefficient is as follows:

[0076] ;

[0077] wherein, is the failure coefficient of the target device for executing the instruction, is the link degradation index, is the standard deviation of the multiple target response delays, is the mean of the multiple target response delays. The coefficient of variation of the target response delay distribution reflects the relative intensity of the target response delay, and indicates the uniformity and stability of the overall delay distribution. For example, whether the overall network delay remains stable in the fluctuation. The link degradation index reflects the absolute intensity of the delay distribution, such as the peak deviation and extreme fluctuation. The greater the value of the round-trip delay, the more significant the fluctuation relative to the average delay, that is, the greater the value, the more unstable the network, and in this case, the instructions in the access control process are prone to delay timeout or sequence disorder, and the unreliability of instruction execution is stronger.

[0078] S12, according to the deviation between the response length of each process variable of the target device for multiple instructions in the same time window and the corresponding preset length, and the failure coefficient, determine the execution delay index.

[0079] The process variables include but are not limited to variables with time sequence characteristics such as temperature, pressure, flow rate, and rotation speed.

[0080] ​The preset time length corresponding to each process variable for each instruction can be obtained by looking up a table. The preset time length is set according to actual conditions, for example, the preset time length of the first process variable for the first instruction is 3s, and the preset time length of the first process variable for the second instruction is 5s. The preset time length indicates the theoretical time length required for each process variable to change from an initial state to a target state after the target device receives each instruction. The response time length indicates the actual time length required for the multiple process variables of the target device to change from the initial state to the target state after the target device receives each instruction.

[0081] The above steps reveal the risk of disorder or retransmission of instruction execution due to unstable network links, so as to evaluate the potential unreliability of instruction execution. However, the effect of instruction execution in the industrial internet environment is not only affected by network delay, and the dynamic change of these instruction execution delays will directly affect the performance of process variables of industrial equipment. Therefore, in one embodiment, an execution delay index is determined according to the deviation between the response time length of each process variable of the target device for multiple instructions in the same time window and the corresponding preset time length, and the failure coefficient, including:

[0082] For each process variable, the mean value of the response time length of each process variable for multiple instructions in the same time window is calculated to obtain the response time length mean value of each process variable, and the mean value of the multiple preset time lengths of each process variable for multiple instructions is calculated to obtain the preset time length mean value of each process variable. Each instruction corresponds to a preset time length for each process variable it regulates. The response time length indicates the time length required for the multiple process variables of the target device to change from an initial state to a target state after the target device receives each instruction.

[0083] The difference between the response time length mean value of each process variable and the corresponding preset time length mean value is calculated to obtain the response time length difference value.

[0084] An execution delay index is determined according to the multiple response time length difference values in each time window and the failure coefficient. The multiple response time length difference values correspond one-to-one to the multiple process variables.

[0085] The main purpose of this step is to conduct in-depth analysis from the physical response level of the device, and then to observe the dynamic deviation influence of the execution time delay on the process variable, and to verify the actual influence degree of the front-end network delay on the field device control, to provide physical feedback basis for dynamic access control strategy.

[0086] Record the response time of the actuator of the target equipment from the initial state to the target state for each process variable after receiving each instruction. Based on this, calculate the average response time of each process variable from the initial state to the target state after receiving multiple instructions within the same time window, which is the average response time of each process variable. This time window is the same as the time window used to collect multiple round-trip delays and multiple response delays. Next, the preset duration for each process variable for each instruction is obtained; that is, the theoretical time required for each process variable to change from its initial state to its target state after the target device receives each instruction. Based on this, the average preset duration for each process variable for multiple instructions is calculated, thus obtaining the average preset duration for each process variable. .

[0087] Calculate the difference between the average response time of each process variable and the corresponding preset average response time to obtain the response time difference. Based on the multiple response time differences of multiple process variables within this time window and the failure coefficient, determine the execution delay index. The calculation formula is:

[0088] ;

[0089] in, To implement the delay index, The number of multiple process variables, For the first One process variable, The failure coefficient for executing instructions on the target device. The mean response time for each process variable, The preset duration average for each process variable.

[0090] Instruction No. The mean response time of the first process variable and the second process variable The absolute difference between the preset mean values ​​of each process variable reflects the time delay between when the equipment receives the instruction and when it should be completed and when it is actually completed. This is a quantifiable objective lag phenomenon. This indicates the unreliability of instruction execution, reflecting a decreased probability that instructions are correctly parsed, transmitted, and executed during the device's operation; in other words, there is potential instability. When both hysteresis and latency coexist and trend in the same direction, it can be inferred that the hysteresis is not random noise, but rather caused by a systemic problem in the device's execution mechanism or transmission link. The larger the value, the greater the execution latency index in the current access control phase.

[0091] S13, determining the influence index of the instruction delay execution on the process variable according to the correlation between the multiple execution delay indexes of the multiple time windows and the change characteristic values of the multiple process variables.

[0092] The control of the target device highly depends on real-time response, and if the execution is delayed, the process variable change will be time-shifted or amplitude-overdriven relative to the target trajectory, which can directly reflect the effect of the control instruction at the device execution layer.

[0093] In one embodiment, the influence index of the instruction delay execution on the process variable is determined according to the correlation between the multiple execution delay indexes of the multiple time windows and the change characteristic values of the multiple process variables, including:

[0094] A coordinate system is established with the time sequence of the multiple time windows as the horizontal axis and the multiple execution delay indexes corresponding to the multiple time windows as the vertical axis, and each data point in the coordinate system is polynomial curve fitted and the vertical coordinate is normalized to obtain an execution curve.

[0095] An independent coordinate system is established for each process variable, with the time sequence number of the multiple time windows as the horizontal coordinate and the variance value of the multiple sampling values of the process variable in each time window as the vertical coordinate, each data point in the coordinate system is polynomial curve fitted and the vertical coordinate is normalized to obtain each change characteristic curve corresponding to each process variable; the multiple sampling values of each process variable corresponding to each time window.

[0096] The mean square errors between the multiple change characteristic curves and the execution delay index curve are calculated respectively, and the obtained mean square errors are averaged to obtain the influence index of the instruction delay execution on the process variable; the multiple process variables and the multiple change characteristic curves correspond one-to-one.

[0097] The multiple time windows include the time window in which the multiple round-trip delays and the multiple response delays are collected, at least one forward time window and / or at least one backward time window which are continuous with the time window on the time axis and have the same window length, and the windows are connected head to tail or partially overlapped. A coordinate system is established with the time sequence of the multiple time windows as the horizontal axis and the multiple execution delay indexes corresponding to the multiple time windows as the vertical axis, and each data point in the coordinate system is polynomial curve fitted and the vertical coordinate is normalized to obtain an execution curve.

[0098] An independent coordinate system is established for each process variable, with the time sequence number of multiple time windows as the x-axis (i.e., the multiple time windows are sorted chronologically), and the sequence number of the multiple time windows as the x-axis. The variance of the multiple sampled values ​​of the process variable within each time window is the y-axis. Polynomial curve fitting is performed on each data point in the coordinate system, and the y-axis is normalized to obtain each characteristic curve corresponding to each process variable. The x-axis coordinates of the multiple process variables in the coordinate system are all one-to-one. In other words, each time window corresponds to multiple sampled values ​​of each process variable, and the variance of the multiple sampled values ​​of the process variable within the same time window can be calculated to obtain the y-axis value corresponding to the x-axis of that time window.

[0099] Map each characteristic curve and execution curve corresponding to each process variable to the same coordinate system, and calculate their mean square error. A smaller mean square error indicates that the variation of this process variable may fluctuate more significantly with increasing execution delay, suggesting a decreasing trend in system stability. Calculate the mean square error between multiple characteristic curves and the execution delay exponential curve, and average the obtained mean square errors to obtain the impact index of instruction delay execution on the process variable. The calculation formula is:

[0100] ;

[0101] in, This is an index representing the impact of instruction delay execution on process variables. The number of multiple process variables, For the first One process variable, To implement the delay index, For the first The mean squared error (MSE) between the characteristic curves of process variables and the execution curve. The MSE is a statistical correlation between changes in execution delay and the fluctuation trend of process variables; the correlation indicates the strength of the driving force of delay changes on the dynamic shift of process variables in the past. This represents the execution latency index during the current time window access control phase. The larger the value, the more sensitive the current delay is to the historical average impact on process variables.

[0102] The above steps, through the impact of execution delay in the access control process on process variables, illustrate that execution delay may cause dynamic shifts in process variables during the execution cycle. However, in the access control process of Internet servers, the executed instructions are often not independent, but rather have dependencies or parallel competition. When the impact of delay is high, the dependency relationship between instructions is more likely to cause system response instability.

[0103] S14, calculate a risk coupling coefficient corresponding to the instruction sequence according to a difference in delay of each adjacent instruction in the instruction sequence.

[0104] wherein the delay of each instruction is obtained by calculating a deviation between a response duration of the plurality of process variables for the same instruction and a corresponding preset duration; and the instruction sequence comprises a plurality of instructions within a plurality of time windows.

[0105] The main purpose of this step is to analyze the influence of the dependency relationship between a plurality of instructions on the access control system, and in the scenario of multiple control links, the delay is often not an isolated risk, but will spread along the dependency chain, and the risk coupling of the instruction sequence can quantify this spreading ability. Therefore, in one embodiment, a risk coupling coefficient corresponding to the instruction sequence is calculated according to a difference in delay of each adjacent instruction in the instruction sequence, including:

[0106] calculating a difference between a mean value of the response duration of the plurality of process variables controlled by each instruction and a mean value of the preset duration of the plurality of process variables controlled by each instruction, to obtain a delay coefficient of each instruction;

[0107] calculating a risk coupling coefficient corresponding to the instruction sequence according to a difference in delay coefficient of each adjacent instruction in the instruction sequence.

[0108] In the current access control process, the mean value of the response duration of the plurality of process variables controlled by each instruction is calculated, and then the mean value of the plurality of preset durations corresponding to the plurality of process variables controlled by each instruction is calculated according to each preset duration corresponding to each process variable controlled by each instruction, to obtain a difference between the mean value of the response duration of the plurality of process variables controlled by each instruction and the mean value of the plurality of preset durations corresponding to the plurality of process variables controlled by each instruction, i.e. the delay coefficient of each instruction .

[0109] In one embodiment, a risk coupling coefficient corresponding to the instruction sequence is calculated according to a difference in delay coefficient of each adjacent instruction in the instruction sequence, including:

[0110] calculating a ratio of the delay coefficient of the adjacent instruction according to a ratio of the delay coefficient of the target instruction to the delay coefficient of the previous instruction of the target instruction; the target instruction being any instruction in the instruction sequence;

[0111] determining a risk coupling coefficient corresponding to the instruction sequence according to an average value of the ratio of the delay coefficient of all adjacent instructions in the instruction sequence.

[0112] In an access control system, the instruction sequence is executed in a fixed order, and the execution of the next instruction depends on the resources (CPU (Central Processing Unit), network bandwidth, database lock, etc.) released by the previous instruction. If the delay of the previous instruction increases, the resource will be occupied for a longer time, causing the start time of the next instruction to be delayed. If this delay is continuously passed between multiple instructions, the delay will be gradually superimposed. The risk coupling coefficient of the instruction sequence in the current access control stage can be calculated, and the risk coupling coefficient corresponding to the instruction sequence The calculation formula of the risk coupling coefficient corresponding to the instruction sequence is as follows:

[0113] ;

[0114] Wherein, is the risk coupling coefficient corresponding to the instruction sequence, is the number of instructions, is the i th instruction, is the delay coefficient of the i th instruction, is the delay coefficient of the i th instruction. The greater the value of the risk coupling coefficient, the greater the cumulative increase in instruction delay, that is, the greater the risk coupling coefficient of the instruction sequence. The delay gradually accumulates, which is the most intuitive external manifestation of the risk coupling mechanism of the instruction sequence, reflecting the continuous amplification of the previous delay on the subsequent delay. Behind this is the physical mechanism of queue backlog or retry amplification after resource occupation. Once the accumulation trend is formed, it will increase the instability of the access control system, that is, it needs to be processed in advance, adjusted, or changed dynamically, and the service is degraded.

[0115] S15, according to the influence index and the risk coupling coefficient, adjusting the number of access instructions of the server.

[0116] In one embodiment, the number of access instructions of the server is adjusted according to the influence index and the risk coupling coefficient, including:

[0117] According to the product of the influence index and the risk coupling coefficient, the access adjustment coefficient of the server is obtained;

[0118] According to the access adjustment coefficient of the server, the number of access instructions of the server is adjusted.

[0119] According to the access adjustment coefficient of the server, the number of access instructions of the server is adjusted.

[0120] ​​The purpose of this step is to meet the demand of dynamically adjusting the access control process of the industrial internet server by combining the dynamic offset effect of the process variable of the risk coupling coefficient and the execution delay of the instruction sequence in the above access control process. Only considering the risk coupling coefficient, it can be determined that the delay will accumulate, but it is not determined whether the delay will really have a greater impact on the process variable, and only considering the dynamic offset response of the execution delay of the process variable, it is determined that the delay will cause process fluctuations, but it is not determined whether the fluctuations caused by the delay are accidental or will be continuously amplified.

[0121] Therefore, the access adjustment coefficient of the server can be obtained according to the product of the influence index and the risk coupling coefficient, and the access adjustment coefficient The calculation formula of the access adjustment coefficient is as follows: ; wherein, is the access adjustment coefficient, is the normalization function, is the risk coupling coefficient corresponding to the instruction sequence, is the influence index of the execution delay of the instruction on the process variable. The larger the access adjustment coefficient is, the higher the risk of causing system instability in the access control process is, that is, the maximum number of access instructions allowed at a time needs to be adjusted.

[0122] In one embodiment, the number of access instructions of the server is adjusted according to the access adjustment coefficient of the server, including:

[0123] The batch adjustment value is obtained according to the sum of the preset value and the access adjustment coefficient;

[0124] The number of access instructions of the server is adjusted according to the product of the absolute difference between the first threshold value and the second threshold value and the batch adjustment value, and the second threshold value. The first threshold value indicates the maximum batch instruction number preset by the server, and the second threshold value indicates the minimum batch instruction number preset by the server.

[0125] The first threshold value and the second threshold value are set according to actual conditions, and the preset value can be 1.

[0126] If the maximum batch instruction number preset by the server is , that is, the maximum batch instruction number allowed in the access control process of the internet server is , and the minimum batch instruction number preset by the server is , the risk coupling coefficient is 0 when the maximum batch instruction number is given to the server, the risk coupling coefficient is 1 when the minimum batch instruction number is given to the server, and the risk coupling coefficient is in (0, 1) Linearly decreases. The maximum batch instruction number allowed in the access control process is adjusted, and the specific steps of the adjustment are as follows: , wherein, ⌊.⌋ is a down rounding function, is the number of access instructions, a minimum batch instruction number preset for the server, a maximum batch instruction number preset for the server, an access adjustment coefficient.

[0127] When the risk coupling coefficient increases, that is, the risk increases, the batch limit is automatically tightened, effectively inhibiting the risk of chain amplification of instruction delay and process variable fluctuation. When the risk coupling coefficient decreases, that is, the risk decreases, the higher batch operation capability is gradually restored, and the production efficiency and network utilization are improved. The minimum time interval and continuous stability judgment rule of batch instruction number adjustment are set to ensure that the newly calculated maximum batch instruction number only triggers the adjustment of the access control parameter when it remains consistent or continuously exceeds the preset threshold in multiple consecutive (such as 3 times) samplings. The preset threshold is set according to the actual situation. At the same time, a hysteresis mechanism is adopted to avoid frequent adjustment of the batch instruction number due to fluctuations near the critical value, thereby improving the stability of the system and the continuity of the access control strategy.

[0128] The present application comprehensively considers the stability of the round-trip delay and the distribution characteristics of the response delay, calculates the failure coefficient, quantifies the risk of instruction out-of-order or retransmission caused by instantaneous instability of the network link, compares the deviation of the response time of each process variable to multiple instructions from the theoretical value, and then superimposes the failure coefficient to obtain the execution delay index, which directly reflects the degree of execution lag of the target device. The correlation between the execution delay index and the process variable change characteristic value in multiple time windows is calculated to generate an influence index, which is used to measure the amplification effect of instruction delay on process fluctuation. The delay difference between adjacent instructions is calculated along the instruction sequence, and the risk coupling coefficient is accumulated to describe the chain amplification trend of delay among multiple instructions. According to the influence index and the risk coupling coefficient, the number of access instructions of the server is adjusted to effectively inhibit the risk of chain amplification of instruction delay and process variable fluctuation, and to ensure the stability and reliability of the industrial internet access control system.

[0129] It should be understood that, although Figure 1 the steps in the flowchart of the method are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order limitation for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 at least part of the steps in the method can include multiple sub-steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily sequential, but can be alternately or alternately executed with at least part of other steps or sub-steps or stages of other steps.

[0130] The present application also provides an access control system of an industrial internet server, such asFigure 2 The system comprises:

[0131] an analysis module 21 configured to analyze the multiple round-trip delays and the multiple response delays to obtain a failure coefficient of the target device executing the instruction; the round-trip delay indicates a time length from the server sending a test data packet to the target device to receiving a response data packet of the target device, and the response delay indicates a time length from the server sending an instruction to the target device to receiving a corresponding service confirmation of the target device;

[0132] a first determination module 22 configured to determine an execution delay index according to a deviation between a response time length of each process variable of the target device to multiple instructions in a same time window and a corresponding preset time length, and the failure coefficient;

[0133] a second determination module 23 configured to determine an influence index of delayed execution of the instruction on the process variable according to a correlation degree between multiple execution delay indexes of multiple time windows and characteristic values of changes of multiple process variables;

[0134] a calculation module 24 configured to calculate a risk coupling coefficient corresponding to an instruction sequence according to a delay difference of each adjacent instruction in the instruction sequence; the delay of each instruction is obtained by calculating a deviation between a response time length of multiple process variables to a same instruction and a corresponding preset time length; the instruction sequence comprises multiple instructions in multiple time windows;

[0135] an adjustment module 25 configured to adjust a number of access instructions of the server according to the influence index and the risk coupling coefficient.

[0136] For the system embodiment, since it basically corresponds to the method embodiment, the relevant parts are described in the method embodiment. The above-described system embodiment is only illustrative, and the units described as separate components can or can not be physically separated, and the components of the unit can or can not be physical units, i.e., they can be located in one place or distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the present application.

[0137] Figure 3 A structure diagram of an electronic device is shown for an example embodiment of the present application, which comprises a memory, a processor, and a computer program stored in the memory and used to run on the processor, and the processor executes the computer program to implement the method described in any of the above embodiments. Figure 3 The electronic device 30 shown is only an example, and should not limit the functions and use range of the embodiments of the present application.

[0138] As Figure 3As shown, the electronic device 30 can be in the form of a general computing device, for example, it can be a server device. The components of the electronic device 30 can include, but are not limited to, the at least one processor 31 described above, the at least one memory 32 described above, a bus 33 that connects the different system components, including the memory 32 and the processor 31.

[0139] The bus 33 includes a data bus, an address bus, and a control bus.

[0140] The memory 32 can include volatile memory, such as random access memory (RAM) 321 and / or cache memory 322, and can further include non-volatile memory, such as read-only memory (ROM) 323.

[0141] The memory 32 can also include a program tool 325 (or utility tool) having a set of one or more program modules 324, such as an operating system, one or more application programs, other program modules, and program data, and can include an implementation of a network environment, for example, in each of these or some combination thereof.

[0142] The processor 31 performs functions of various embodiments provided by the computer program instructions, such as the methods described above, by operating in accordance with the computer program instructions stored in the memory 32.

[0143] The electronic device 30 can also communicate with one or more external devices 34 (such as a keyboard or a pointing device, for example) by way of an input / output (I / O) interface 35. Additionally, the electronic device 30 can communicate with one or more networks, such as a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet, by way of a network adapter 36. As illustrated, the network adapter 36 communicates with the other modules of the electronic device 30 by way of the bus 33. It should be appreciated that other hardware and / or software modules can be used in conjunction with the electronic device 30, such as, for example, microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data archival storage systems, etc.

[0144] It should be noted that although several units / modules or sub-units / modules of the electronic device are mentioned in the foregoing detailed description, such division is merely exemplary and not mandatory. Indeed, according to embodiments of the present application, features and functions of two or more units / modules described above can be embodied in one unit / module. Conversely, features and functions of one unit / module described above can be further divided into a plurality of units / modules.

[0145] The embodiment of the present application further provides a computer readable storage medium, which stores a computer program, and the program is executed by a processor to implement the method provided by any of the above embodiments.

[0146] More specifically, the readable storage medium can include, but is not limited to, a portable disc, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory, an optical storage device, a magnetic storage device or any suitable combination of the above.

[0147] It is understood by those skilled in the art that all or part of the processes of the above-mentioned embodiments can be completed by a computer program instructing related hardware, and the computer program can be stored in a non-volatile computer readable storage medium. When the computer program is executed, the computer program can include the processes of the above-mentioned embodiments. Any reference to memory, storage, database or other medium used in the embodiments provided by the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct RAM bus dynamic RAM (DRDRAM) and memory bus dynamic RAM (RDRAM) and the like.

[0148] The embodiment of the present application further provides a computer program product, which includes a computer program, and the computer program is executed by a processor to implement the method provided by any of the above embodiments.

[0149] The program code of the computer program product for executing the present application can be written in any combination of one or more programming languages, and can be executed completely on a user device, partially on a user device, as a separate software package, partially on a user device and partially on a remote device, or completely on a remote device.

[0150] Any technical features in the above embodiments can be combined, and for the sake of brevity, not all possible combinations are described, however, any combination of the technical features is deemed to be within the scope of the present disclosure.

[0151] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the application. It should be pointed out that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these are within the protection scope of the present application.

[0152] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment mainly describes the difference from other embodiments.

Claims

1. An access control method of an industrial internet server, characterized by, The method comprises: analyzing a plurality of round-trip delays and a plurality of response delays to obtain a failure coefficient of the target device executing instructions; the round-trip delay indicates the time length from the server sending a test data packet to the target device to receiving a response data packet thereof; the response delay indicates the time length from the server sending an instruction to the target device to receiving a corresponding service confirmation response thereof; determining an execution delay index according to the deviation between the response time length of each process variable of the target device to a plurality of instructions within the same time window and the corresponding preset time length, and the failure coefficient; determining an influence index of delayed execution of instructions on process variables according to the correlation between a plurality of execution delay indexes of a plurality of time windows and characteristic values of changes of a plurality of process variables; calculating a risk coupling coefficient corresponding to an instruction sequence according to the delay difference of each adjacent instruction in the instruction sequence; the delay of each instruction is obtained by calculating the deviation between the response time length of a plurality of process variables to the same instruction and the corresponding preset time length; the instruction sequence comprises a plurality of instructions within a plurality of time windows; adjusting the number of access instructions of the server according to the influence index and the risk coupling coefficient; The method comprises: collecting a plurality of round-trip delays and a plurality of response delays within the same time window; establishing a coordinate system with a plurality of collection time points within the time window as the horizontal axis and a plurality of round-trip delays as the vertical axis, and performing linear interpolation on each data point in the coordinate system to obtain a round-trip delay broken line, and calculating the slope value between all adjacent data points in the round-trip delay broken line; the plurality of collection time points and the plurality of round-trip delays correspond to each other; determining a link degradation index according to the range value of the round-trip delay within the time window and the absolute difference value between each adjacent slope value; analyzing the link degradation index and a plurality of response delays to obtain a failure coefficient of the target device executing instructions. 2.The method of claim 1, wherein, The method comprises: obtaining the sending time of the server sending an instruction to the target device, the response delay of the instruction, and the identification information of the instruction within the same time window; corresponding to each instruction, in response to retrieving the corresponding service confirmation response within the same time window according to the identification information of the instruction, determining the time length between the sending time of the instruction and the corresponding service confirmation response as the target response delay; determining the failure coefficient according to the standard deviation of a plurality of target response delays, the mean of a plurality of target response delays, and the link degradation index. 3.The method of claim 1, wherein, The method comprises: For each process variable, the mean value of the response duration of each process variable for multiple instructions within the same time window is calculated to obtain the response duration mean value of each process variable, and the mean value of multiple preset durations of each process variable for multiple instructions is calculated to obtain the preset duration mean value of each process variable; each instruction corresponds to a preset duration for each process variable it regulates; the response duration indicates the time length required for multiple process variables of the target device to change from an initial state to a target state after the target device receives each instruction; The difference between the response duration mean value and the corresponding preset duration mean value of each process variable is calculated to obtain the response duration difference value; According to the multiple response duration difference values within each time window and the failure coefficient, the execution delay index is determined; the multiple response duration difference values correspond to the multiple process variables one by one. 4.The method of claim 1, wherein The correlation between the multiple execution delay indexes of the multiple time windows and the change characteristic values of the multiple process variables is determined to obtain the influence index of instruction delayed execution on process variables, including: A coordinate system is established with the time sequence of the multiple time windows as the horizontal axis and the multiple execution delay indexes corresponding to the multiple time windows as the vertical axis, polynomial curve fitting is performed on each data point in the coordinate system, and the vertical coordinates are normalized to obtain an execution curve; An independent coordinate system is established for each process variable, the time sequence number of the multiple time windows is taken as the horizontal coordinate, and the variance value of the multiple sampling values of the process variable within each time window is taken as the vertical coordinate, polynomial curve fitting is performed on each data point in the coordinate system, and the vertical coordinates are normalized to obtain each change characteristic curve corresponding to each process variable; each time window corresponds to multiple sampling values of each process variable; The mean square errors between the multiple change characteristic curves and the execution delay index curve are calculated respectively, and the obtained mean square errors are averaged to obtain the influence index of instruction delayed execution on process variables; the multiple process variables correspond to the multiple change characteristic curves one by one. 5.The method of claim 3, wherein, The difference between the response duration mean value and the corresponding preset duration mean value of each process variable is calculated to obtain the response duration difference value; According to the multiple response duration difference values within each time window and the failure coefficient, the execution delay index is determined; the multiple response duration difference values correspond to the multiple process variables one by one. The correlation between the multiple execution delay indexes of the multiple time windows and the change characteristic values of the multiple process variables is determined to obtain the influence index of instruction delayed execution on process variables, including:

6. The access control method of an industrial internet server according to claim 5, wherein, The ratio of the delay coefficients of adjacent instructions is calculated according to the ratio of the delay coefficients of the target instruction and the previous instruction of the target instruction; the target instruction is any instruction in the instruction sequence; The risk coupling coefficient corresponding to the instruction sequence is determined according to the average value of the ratios of the delay coefficients of all adjacent instructions in the instruction sequence. The access instruction quantity of the server is adjusted according to the influence index and the risk coupling coefficient, including: 7.The method of claim 1, wherein, The access adjustment coefficient of the server is obtained according to the product of the influence index and the risk coupling coefficient; The access instruction quantity of the server is adjusted according to the access adjustment coefficient of the server. ​ 8.The method of claim 7, wherein, The access instruction quantity of the server is adjusted according to the access adjustment coefficient of the server, and the adjusting comprises: A batch adjustment value is obtained according to a sum of a preset value and the access adjustment coefficient; The access instruction quantity of the server is adjusted according to a product of an absolute difference between a first threshold value and a second threshold value and the batch adjustment value and the second threshold value; the first threshold value indicates a preset maximum batch instruction number of the server, and the second threshold value indicates a preset minimum batch instruction number of the server.

9. An access control system of an industrial internet server, characterized by, The system comprises: An analysis module is configured to analyze a plurality of round-trip delays and a plurality of response delays to obtain a failure coefficient of a target device executing an instruction; the round-trip delay indicates a time length from sending a test data packet to the target device by the server to receiving a response data packet; and the response delay indicates a time length from sending an instruction to the target device by the server to receiving a corresponding service confirmation; A first determination module is configured to determine an execution delay index according to a deviation between a response time length of each process variable of the target device to a plurality of instructions in a same time window and a corresponding preset time length and the failure coefficient; A second determination module is configured to determine an influence index of delayed execution of an instruction on a process variable according to a correlation between a plurality of execution delay indexes of a plurality of time windows and a change characteristic value of a plurality of process variables; A calculation module is configured to calculate a risk coupling coefficient corresponding to an instruction sequence according to a delay difference between each adjacent instruction in the instruction sequence; the delay of each instruction is obtained by calculating a deviation between a response time length of a plurality of process variables to a same instruction and a corresponding preset time length; and the instruction sequence comprises a plurality of instructions in a plurality of time windows; An adjustment module is configured to adjust an access instruction quantity of the server according to the influence index and the risk coupling coefficient. The analysis of the plurality of round-trip delays and the plurality of response delays to obtain the failure coefficient of the target device executing the instruction comprises: A plurality of round-trip delays and a plurality of response delays in a same time window are collected; A coordinate system is established with a plurality of collection time points in the time window as an abscissa and the plurality of round-trip delays as an ordinate, and linear interpolation is performed on each data point in the coordinate system to obtain a round-trip delay broken line and calculate a slope value between all adjacent data points in the round-trip delay broken line; the plurality of collection time points and the plurality of round-trip delays correspond to each other; A link degradation index is determined according to a range value of the round-trip delays in the time window and an absolute difference between each adjacent slope value; The link degradation index and the plurality of response delays are analyzed to obtain the failure coefficient of the target device executing the instruction.

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