A Deterministic Analysis Method for VOQ Switch Communication Based on Network Calculus

Abstract

The present invention belongs to the communication technology field of high-speed time-triggered networks in distributed real-time systems, and in particular, relates to a VOQ switch communication deterministic analysis method based on network calculation, including: defining a communication deterministic analysis model: the TT message deterministic analysis model is defined as: for TT messages in the VOQ switch, deterministic analysis is performed according to the receiving window and the sending window in the communication configuration table; the RC message deterministic analysis model is defined as: for RC messages in the VOQ switch, deterministic analysis is performed according to the sending cycle in the communication configuration table and using a network calculation method, supporting switch communication delay deterministic analysis to meet the needs of the increasing application scope of time-triggered networks.

Description

Technical Field

[0001] The present invention belongs to the technical field of communication of high-speed time-triggered networks in distributed real-time systems, and in particular to a VOQ switch communication deterministic analysis method based on network calculation. Background Art

[0002] Compared with traditional event-triggered networks, time-triggered networks (TT networks) have good communication determinism and can meet the needs of hard real-time communication in real-time systems. They have broad application space in real-time systems such as aerospace, high-speed railways, and automotive electronics. Time-triggered networks usually require the simultaneous support of time-triggered messages and event-triggered messages to meet the needs of mixed transmission of strong real-time data and general real-time data. Whether it is strong real-time data or general real-time data communication, data communication needs to be completed within the specified time range to achieve deterministic communication. High-speed time-triggered network switches usually use the VOQ (virtual output queue) mechanism for communication scheduling. In VOQ switches, it is necessary to support the mixed scheduling of time-triggered messages and rate-limited event-triggered messages. Time-triggered messages (TT messages for short) are communicated based on global time, and rate-limited event-triggered messages (RC messages for short) ensure that messages are transmitted within a message cycle.

[0003] The memory bandwidth of VOQ switches is only related to the port rate and has nothing to do with the number of ports on the switch. It is suitable for the development of high-density high-speed switches and meets the communication needs of gigabit high-speed switching networks. VOQ switches have been widely used in high-speed switching networks. However, the message queue of the VOQ switch is in the input port, and the data exchange delay will be affected by the load of other ports, resulting in the message transmission delay being related to the actual load, which is uncertain and affects the application of VOQ switches in real-time systems such as avionics. Summary of the invention

[0004] The purpose of the present invention is to provide a communication deterministic analysis method for a VOQ switch in a time-triggered network, supporting deterministic analysis of switch communication delays to meet the needs of the ever-increasing application scope of time-triggered networks.

[0005] The technical solution of the present invention:

[0006] A VOQ switch communication deterministic analysis method based on network calculation, the method comprising:

[0007] Defining a communication deterministic analysis model: the communication deterministic analysis model includes a TT message deterministic analysis model and an RC message deterministic analysis model;

[0008] The TT message deterministic analysis model is defined as: for the TT message in the VOQ switch, a deterministic analysis is performed according to the receiving window and the sending window in the communication configuration table;

[0009] The RC message deterministic analysis model is defined as: for the RC message in the VOQ switch, a deterministic analysis is performed according to the sending cycle in the communication configuration table and using a network calculation method.

[0010] Furthermore, the priority of the TT message is higher than that of the RC message, and the deterministic analysis of the TT message will affect the deterministic analysis of the RC message, while the deterministic analysis of the RC message will not affect the deterministic analysis of the TT message.

[0011] Furthermore, the maximum delay of the TT message in the VOQ switch is the maximum interval between the start time of the receiving window and the start time of the sending window.

[0012] Furthermore, the deterministic analysis process of the RC message in the VOQ switch is as follows:

[0013] S1, determine the arrival curve of the RC message;

[0014] S2, determine the service curve of the RC message;

[0015] S3, determine the technical delay of the RC message;

[0016] S4, obtaining the RC message delay according to the arrival curve, service curve and technical delay of the RC message.

[0017] Furthermore, S1 is specifically:

[0018] The arrival curve formula of RC message is:

[0019] in: is the i-th RC message RC i Maximum frame length; is the i-th RC message RC i The minimum frame interval.

[0020] Furthermore, S2 is specifically:

[0021] If a VOQ switch has N input ports, the current input port receives a flow that includes M TT messages and K RC messages destined for the same output port, and the total rate of the output port is C, the service curve formula is:

[0022]

[0023] Where: C -RC It indicates the remaining service capacity after the output end transmits the traffic allocated to TT. Indicates non-i-th RC message RC i The total service capacity occupied by other RC traffic of B -RC Represents the sum of high priority data frames, Indicates non-i-th RC message RC i The sum of other RC data frames;

[0024]

[0025]

[0026]

[0027]

[0028] in, Indicates the maximum sending rate of the mth TT traffic, represents the maximum sending rate of the kth RC traffic, represents the maximum sending rate of the i-th RC traffic, Indicates the maximum data frame of the mth TT traffic, represents the maximum data frame of the k-th RC traffic, Indicates the maximum data frame of the i-th RC flow.

[0029] Furthermore, S3 is specifically: the maximum lateral distance between the arrival curve and the service curve RC service delay for the current data frame.

[0030] Furthermore, S4 is specifically:

[0031] The i-th RC message RC i The delay D i :

[0032]

[0033]

[0034]

[0035] D VOQ·in Representative and RC i The longest data frame in all other queues with the same input port but different output ports Technical delay caused by priority processing during input port idle detection;

[0036] D VOQ·out Representative and RC iThe longest data frame in all other queues of different input ports and output ports Technical delay caused by priority processing during output port idle detection.

[0037] The beneficial effects of the present invention are as follows: the present invention establishes a technical foundation for the application of high-speed VOQ switches in real-time systems such as avionics through deterministic analysis of VOQ switch communication messages. The analyzed messages include TT messages and RC messages, which can meet the needs of both strong real-time communication task analysis and general real-time communication task deterministic analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of an embodiment of a time-triggered network switch transmission model;

[0039] Figure 2 Definition of a delay analysis model based on network calculation according to the present invention;

[0040] Figure 3 This is an embodiment of the deterministic analysis method of the present invention. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0042] In practical applications, strong real-time message communication tasks have very high requirements for real-time transmission and can use a time trigger mechanism for communication, while general real-time communication tasks have relatively weaker requirements for real-time performance and can use event triggering for communication. According to this feature of real-time system communication tasks, the present invention achieves the purpose of the present invention by defining a VOQ switch communication deterministic analysis model based on network calculation. The communication deterministic analysis model includes a TT message deterministic analysis model and an RC message deterministic analysis model. The TT message generated by the strong real-time communication task enters the TT message deterministic analysis model according to the receiving time window defined in the communication configuration table. The model performs message deterministic analysis according to the receiving time window and sending time window defined in the configuration table. The RC message generated by the general real-time communication task enters the RC message deterministic analysis model according to the sending period defined in the configuration table. The model uses a network calculation method to perform deterministic analysis on the message.

[0043] The communication deterministic analysis model has the following implementation features:

[0044] AFor the TT message in the VOQ switch, the analysis is strictly carried out according to the receiving time window and the sending time window. The RC message will not affect the analysis process of the TT message.

[0045] B uses network calculation method to analyze the RC message defined in VOQ switch, such as Figure 2As shown in the figure, the TT message has a higher priority than the RC message, which will affect the analysis process of the RC message.

[0046] The server adopts an offline mode and analyzes the input communication task according to the deterministic analysis model of the present invention to form the worst transmission delay of the message. The time-triggered network communication equipment (including node machines and switches) needs to strictly send and receive data according to the communication configuration table.

[0047] The following paragraphs show an embodiment of the method of the invention with a possible example, in which the switch defines three communication ports. Communication port 0 is connected to an offline computing server node. Before the switch is running, the server node uses an offline method to perform deterministic analysis on the message based on the deterministic analysis model, and the configuration of the completed analysis is loaded into the switch. The server node is connected to the switch through the management port and does not participate in time-triggered communication. Communication port 1 and communication port 2 defined by the switch can be connected to two node machines to form a network system.

[0048] The present invention is further described in detail below according to the accompanying drawings and embodiments:

[0049] Figure 1 The schematic diagram of the composition of switch 1 is shown. The switch includes 3 communication ports, communication port 0 is a management port, connected to the server, and used to load the communication configuration table. The communication configuration table that has undergone deterministic analysis in the server is loaded into the switch through communication port 0. Input port 1 and output port 1 constitute communication port 1, and input port 2 and output port 2 constitute communication port 2.

[0050] If the TT message sent by the strong real-time communication task arrives at the switch port earlier than the time configured in the configuration table, it needs to be buffered to form a TT queue until the time specified in the configuration table is reached for data communication. There are many ways to handle TT data that does not meet the configuration requirements of the configuration table during communication. It can be discarded or delayed. The RC message sent by the general real-time communication task enters the switch port and also needs to be buffered to form an RC queue. The switch performs communication scheduling according to the communication scheduling algorithm.

[0051] According to the design of VOQ switch, the input port has VOQ queues, which are used to store the queues arriving at each output port. For TT and RC messages, a TT queue and an RC queue are formed for each output port in the input port. Figure 1 In the example, port 1 includes four queues, namely the TT and RC queues arriving at output port 1 and the TT and RC queues arriving at output port 2.

[0052] exist Figure 1In the figure, the TT queue sent from input port 1 to output port 1 includes TT message M11, and the RC queue includes RC messages M12 and M13; the TT queue sent from input port 1 to output port 2 includes TT message M14, and the RC queue includes RC messages M15 and M16; the TT queue sent from input port 2 to output port 1 includes TT message M21, and the RC queue includes RC messages M22 and M23; the TT queue sent from input port 2 to output port 2 includes TT message M24, and the RC queue includes RC messages M25 and M26.

[0053] TT messages M11, M14, M21, and M24 arrive according to the receiving time window defined in the configuration table. Since TT data transmission is driven according to the configuration table, there is no communication conflict in the switch during data exchange, ensuring the transmission of real-time data. The transmission times of M11, M14, M21, and M24 messages do not conflict with each other.

[0054] RC messages M12, M13, M15, M16, M22, M23, M25, and M26 arrive according to the cycle defined in the configuration table. When RC messages are transmitted, if they conflict with TT, the data needs to be buffered until there is no conflict. When RC messages M12 / M13, M15 / M16, M22 / M23, M25 / M26 conflict with TT messages M11, M14, M21, and M24, they are buffered in the queue to ensure priority transmission of TT messages and forward data when the link is idle.

[0055] The communication deterministic analysis model includes the TT message deterministic analysis model and the RC message deterministic analysis model.

[0056] Definition of the TT message deterministic analysis model: In a basic cycle of the TT data frame in the switch, the receiving window time interval and the sending window time interval are configured. The switch only provides reception or transmission processing of TT data frames within the window time. The maximum delay is the maximum interval between the start time of the receiving window and the start time of the sending window:

[0057]

[0058] Where: T IgWinStart is the start time of the receiving window; T EgWinStart The start time of the sending window.

[0059] In the above A, the TT message analysis is strictly performed according to the time window, and the RC message will not affect the deterministic analysis of the TT message.

[0060] In the above B, the RC message is analyzed using the network calculation method, and the TT message has a higher priority than the RC message, which will affect the analysis of the RC message. Figure 2 Definition of RC message analysis model for VOQ switches.

[0061] In the switch, RC traffic forwarding does not need to strictly guarantee the sending time. It is a priority-based continuous sending data flow, which has a lower priority than TT and is queued in the VOQ of the input port. It does not need to be queued at the output port. Since the switch polls to detect whether the input port and output port are idle when forwarding data frames, the message forwarding can only be processed after the port is idle. Therefore, considering that in the worst case, the data frames of all other input ports of the switch may cause an idle waiting technical delay for the target flow, this delay needs to be added to the target flow service curve formula.

[0062] Since the arrival rate of RC frames is constrained by traffic shaping, the arrival curve formula of RC data flow is:

[0063]

[0064] in: For RC i Maximum frame length; For RC i The minimum frame interval.

[0065] When obtaining the service curve, the service rate available to the low-priority communication flow is limited by the high-priority communication flow. If the switch has N input ports, the current input port receives M TT message flows and K RC message flows to the same output port, and the γ TT|RC Indicates the maximum sending rate of different traffic, b TT|RC Indicates its maximum data frame, the total rate of the output port is C, from which an equivalent service curve can be obtained. The formula of the equivalent service curve is:

[0066]

[0067] in:

[0068] C -RC It indicates the remaining service capacity after the output end transmits the allocated TT traffic, that is:

[0069]

[0070] Indicates non The total service capacity occupied by other RC traffic, that is:

[0071]

[0072] B -RC Represents the sum of high priority data frames, that is:

[0073]

[0074] Indicates non-RC i The sum of other RC data frames, namely:

[0075]

[0076] Maximum lateral distance according to the arrival curve and service curve is the RC service delay of the current data frame, and in addition, a VOQ idle waiting technical delay D caused by other queues with the same input port but different output ports needs to be superimposed. VOQ·in , and the VOQ idle waiting technical delay D caused by other queues of different input ports and output ports VOQ·out .

[0077] D VOQin Representative and RC i The technical delay caused by the longest data frame in other queues of the same input port but different output ports being processed first during the input port idle detection;

[0078]

[0079] D VOQ·out Representative and RC i Technical delay caused by the longest data frame in other queues of different input ports and output ports being processed first during output port idle detection:

[0080]

[0081] RC message delay D i :

[0082] Figure 3 This is an embodiment of the VOQ switch communication deterministic analysis tool based on network calculation of the present invention, and the specific process is as follows:

[0083] 1) Initialization is performed first. Import the ICD (Interface Control Document) file to determine the integrity of the switch communication message parameters, including message ID number, message cycle, message type, message delay constraint, etc.; import the communication configuration table to determine the integrity of the message configuration.

[0084] 2) After initialization is completed, check all message parameters and configuration parameters to analyze whether the TT message time window conflicts. Check whether each TT message and RC message has a configuration definition in the configuration file. If the parameter check fails, the analysis process ends, otherwise proceed to step 3.

[0085] 3) For the VOQ switch, a switch transmission model is established, including the TT message queue and RC message queue of the VOQ switch.

[0086] 4) Establish a deterministic analysis model and conduct communication deterministic analysis:

[0087] For TT messages, a TT message deterministic analysis model is formed, and the delay of each TT message is calculated.

[0088] For RC messages, a deterministic analysis model for RC messages is formed, including the arrival curve and service curve of each message, and the RC message service delay is calculated. Based on the analysis model, combined with the VOQ idle waiting technology delay, the RC message delay is calculated.

[0089] 5) Determine whether all calculated message delays meet the communication delay constraint requirements. If not, display the unsatisfied message information. Otherwise, the communication delays of all messages meet the requirements and the analysis process ends.

[0090] VOQ switches have been widely used in high-speed switching networks. The message queue of the VOQ switch is in the input port, and the message transmission delay is related to the actual load, resulting in uncertainty in communication delay, which affects the application of VOQ switches in real-time systems such as avionics. The present invention establishes a technical foundation for the application of high-speed VOQ switches in real-time systems such as avionics through deterministic analysis of VOQ switch communication based on network calculation. The analyzed messages include TT messages and RC messages, which can meet the needs of deterministic analysis of strong real-time communication messages as well as the needs of deterministic analysis of general real-time messages.

[0091] The purpose of the present invention is to provide a communication deterministic analysis method and analysis tool for VOQ switches in a time-triggered network, supporting deterministic analysis of switch communication delays to meet the increasing needs of the application scope of time-triggered networks. The project results are also applicable to deterministic analysis of event-triggered networks based on VOQ switches. The present invention implements the communication deterministic analysis of VOQ switches by using a network calculation method to achieve the purpose of the present invention. Among them, for the TT messages in the VOQ switch, the analysis is strictly performed according to the time window, and the RC message will not affect the analysis of the TT message. For the RC message defined in the VOQ switch, the network calculation method is used for analysis, and the priority of the TT message is higher than that of the RC message, which will affect the analysis of the RC message. The above-mentioned specific embodiment of the present invention only represents one of the many possibilities for the implementation of the present invention. The present invention can also be used in conjunction with other deterministic analysis methods.

Claims

1. A VOQ switch communication deterministic analysis method based on network calculation, characterized in that: The method comprises: Defining a communication deterministic analysis model: the communication deterministic analysis model includes a TT message deterministic analysis model and an RC message deterministic analysis model; the priority of a TT message is higher than that of an RC message, the deterministic analysis of a TT message will affect the deterministic analysis of an RC message, while the deterministic analysis of an RC message will not affect the deterministic analysis of a TT message; The TT message deterministic analysis model is defined as: for the TT message in the VOQ switch, a deterministic analysis is performed according to the receiving window and the sending window in the communication configuration table; the maximum delay of the TT message in the VOQ switch is the maximum interval between the start time of the receiving window and the start time of the sending window; The RC message deterministic analysis model is defined as: for the RC message in the VOQ switch, a deterministic analysis is performed according to the sending cycle in the communication configuration table and using a network calculation method; The deterministic analysis process of the RC message in the VOQ switch is as follows: S1, determine the arrival curve of the RC message; S2, determine the service curve of the RC message; S3, determine the technical delay of the RC message; S4, obtaining the RC message delay according to the arrival curve, service curve and technical delay of the RC message.

2. According to claim 1, a VOQ switch communication deterministic analysis method based on network calculation is characterized in that: S1 is specifically: The arrival curve formula of RC message is: in: is the i-th RC message RC i Maximum frame length; is the i-th RC message RC i The minimum frame interval.

3. The method for analyzing VOQ switch communication determinism based on network calculation according to claim 1, characterized in that: S2 is specifically: If a VOQ switch has N input ports, the current input port receives a flow that includes M TT messages and K RC messages destined for the same output port, and the total rate of the output port is C, the service curve formula is: Where: C -RC It represents the remaining service capacity after the output end transmits the traffic allocated to TT. Indicates non-i-th RC message RC i The total service capacity occupied by other RC traffic of B -RC Represents the sum of high priority data frames, Indicates non-i-th RC message RC i The sum of other RC data frames; in, Indicates the maximum sending rate of the mth TT traffic, represents the maximum sending rate of the kth RC traffic, represents the maximum sending rate of the i-th RC traffic, Indicates the maximum data frame of the mth TT traffic, represents the maximum data frame of the k-th RC traffic, Indicates the maximum data frame of the i-th RC flow.

4. The method for analyzing VOQ switch communication determinism based on network calculation according to claim 3, characterized in that: S3 is specifically: the maximum lateral distance between the arrival curve and the service curve RC service delay for the current data frame.

5. A VOQ switch communication deterministic analysis method based on network calculation according to claim 4, characterized in that: S4 is specifically: The i-th RC message RC i The delay D i : D VOQ.in Representative and RC i The longest data frame in all other queues with the same input port but different output ports Technical delay caused by priority processing during input port idle detection; D VOQ.out Representative and RC i The longest data frame in all other queues of different input ports and output ports Technical delay caused by priority processing during output port idle detection.

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