End-to-end low latency scheduling method for time-sensitive network time-triggered flows

Abstract

The application relates to an end-to-end low-delay scheduling method of a time-sensitive network time trigger flow, belongs to the field of industrial internet, and comprises the following steps: S1, acquiring information of all TT flows of a switch, and performing time slot allocation on all links through which all TT flows pass from a source node to a destination node according to the priority size; S2, reducing the end-to-end delay of the TT flow through local time slot searching; and S3, according to the optimized time slot occupation table, reducing the number of time-aware shapers as much as possible, reducing the opening door times, and generating a corresponding door control list. The application reduces the end-to-end delay of the TT flow and also reduces the number of time-aware shapers.

Description

Technical Field

[0001] This invention belongs to the field of industrial internet and relates to an end-to-end low-latency scheduling method for time-sensitive network time-triggered streams. Background Technology

[0002] Time-Sensitive Networking (TSN) is a set of standards designed to improve the real-time performance of current Ethernet networks. It encompasses a series of standards defined within the TSN task group of the IEEE 802.1 standardization organization. Due to the recent increase in demands for functionality in industrial systems, data communication in these systems faces numerous challenges. For example, autonomous vehicles and smart factories utilize a wide range of complex intelligent sensors and cameras, requiring significant communication bandwidth. Meeting their timing requirements, coupled with high data exchange volumes, necessitates ensuring deterministic transmission. This places further pressure on the data communication design of such systems. Time-Sensitive Networking primarily addresses these challenges through deterministic flow scheduling (IEEE 802.1Qbv) and enhanced time synchronization (IEEE 802.1AS).

[0003] Although IEEE 802.1Qbv proposed a mechanism for communication scheduling information in TSNs, users still need to propose a gating list. In time-sensitive networks, the latency that can be optimized by the scheduling decision-maker mainly lies in the switch. Figure 1 As shown, in a time-sensitive network, the time-triggered flow extends from the source node to the destination node by D. ETE Due to transmission delay Propagation delay Processing latency and queuing delay It consists of four parts, namely:

[0004]

[0005] In local area networks (LANs), the transmission length is generally short, and the propagation delay is significant compared to the propagation speed of electromagnetic waves in the channel. Negligible; latency occurring within the switch includes: transmission latency. Processing latency Queue delay Including transmission delay It is related to the message length and the transmission speed of the switch port, that is:

[0006]

[0007] Processing latency Related to the performance of the switch, it is generally considered a constant.

[0008] Queue delay The latency is caused by data frames waiting in the switch's queuing buffer, such as... Figure 2 As shown, when two frames arrive at the switch at the same time, one frame will inevitably be sent first and the other later, resulting in a queuing delay for the later-sent frame. Current technology cannot minimize this queuing delay. Summary of the Invention

[0009] In view of this, the purpose of this invention is to provide an end-to-end low-latency scheduling method for time-sensitive network time-triggered flows.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] An end-to-end low-latency scheduling method for time-sensitive network time-triggered streams includes the following steps:

[0012] S1: Obtain information on all TT flows from the switch and allocate time slots for all links traversed by all TT flows from the source node to the destination node according to their priority.

[0013] S2: Reduce end-to-end delay of TT stream through local time slot search;

[0014] S3: Based on the optimized time slot occupancy table, minimize the number of time-aware shapers and the number of door openings, and generate the corresponding door control list.

[0015] Furthermore, step S1 specifically includes:

[0016] S11: Read and collect information on all TT streams in the network, including the period, packet size, and priority information of the TT streams;

[0017] S12: Sort all TT streams in descending order of priority, and calculate the overall scheduling period T of the TT streams. A And calculate each TT stream Relative to the comprehensive scheduling period T A The number of transmission frames N i And the basic unit for calculating time slot transmission, the slot;

[0018] S13: Select the first TT stream And select the first link of the TT stream according to the path. Determine the occupancy variable of the i-th time slot of this link from node m to node n. If the value is not equal to 1, then the next transmission will be occupied. Required time slots And Set to 1; if the current time slot This means the current time slot is occupied; skip the current time slot and select the next time slot. And repeat step S13;

[0019] S14: Let N i =N i -1, determine N i Is N ≠ 0? i If the time interval is not equal to 0, then add the time occupied by this time slot. Period T i And occupy it again, that is: make And make N i =N i -1, where This indicates that time slot i is within time slot length T. i In subsequent time slots, repeat step S14 until N. i =0;

[0020] S15: Determine the TT flow Have all time slots been allocated for all the links traversed? If not, select the next link.

[0021] S16: Determine whether all TT streams have been scheduled. If not, select the next TT stream and proceed to step S13.

[0022] S17: After steps S11-S16, a preliminary time slot occupancy table is obtained and output.

[0023] Furthermore, the comprehensive scheduling period T mentioned in step S12 A for:

[0024] T A =LCM(T1, T2, ..., T) i )

[0025] Where LCM represents the least common multiple, T1~T i Indicates TT stream The cycle;

[0026] Each TT stream Relative to the comprehensive scheduling period T A The number of transmission frames N i The calculation is as follows:

[0027]

[0028] The basic unit of time slot transmission, Slot, is:

[0029]

[0030] Where GCD represents the greatest common divisor. Indicates TT stream Required time slot size:

[0031]

[0032] SP s Indicates the transmission speed of the switch port. Indicates TT stream The size of the data frame.

[0033] Furthermore, step S2, which describes reducing the end-to-end delay of the TT stream through local time slot search, specifically includes:

[0034] S21: Read the preliminary time slot occupancy table and select the first TT stream. Select the link closest to the destination node;

[0035] S22: From the lowest priority TT stream Start searching, select On links closer to the destination node, select TT flow. The occupancy variable of the i-th time slot from node m to node n The time slot; starting from that time slot, search backwards to determine... In adjacent links Is there an idle time slot, i.e., TT stream? The occupancy variable of the i-th time slot from node n to node o If there is one, proceed to step S23; otherwise, select the next link. After the link is determined, select the next TT flow.

[0036] S23: Determine whether it is possible to... In the link The time slot occupied by the previous slot is moved forward, and then it is determined whether the time slot can be reduced after the movement. If there is end-to-end delay, the spare time slots are eliminated by shifting the time slot occupancy and the time slot occupancy table is updated. If the end-to-end delay cannot be reduced, the next link is selected.

[0037] S24: Check if all TT streams have been optimized. If all have been optimized, generate an optimized timeslot occupancy table.

[0038] Furthermore, step S3 specifically includes:

[0039] S31: Read the time slot occupancy table generated after time slot occupancy optimization, and select the time slot occupancy table of the first link;

[0040] S32: Select the first time slot of the link, and determine... Is it equal to 1? If Head Then determine if the priorities of the TT streams occupying these two time slots are equal. If they are equal, merge the two time slots; otherwise, select the next time slot. Head. Then the two unoccupied time slots will be merged; this process continues until the last time slot of the current link is reached.

[0041] S33: Select the first time slot of the link, and determine... Is it equal to 1? If Then the gate list parameters are generated, and the gate priority parameter is... The binary number, according to Slot i The size of the time slot determines the time slot parameters; if Then set the gating priority parameter to all 1s, according to the Slot. i The time slot size determines the time slot parameters; this process continues until the last time slot of the current link is reached.

[0042] S34: Check if gating lists have been generated for all links. If gating lists have been generated for all links, output the generated gating lists. If there are still links for which gating lists have not been generated, select those links and repeat steps S32-S33.

[0043] The beneficial effects of this invention are as follows: Compared with the traditional strict priority algorithm, this scheme optimizes the end-to-end delay and the number of time slots, which can reduce the end-to-end delay of TT streams and also reduce the number of time-aware shapers.

[0044] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0045] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0046] Figure 1 This is a diagram illustrating the latency of the TSN network.

[0047] Figure 2 This is a diagram illustrating queuing delays.

[0048] Figure 3 This is a diagram illustrating the door opening and closing times.

[0049] Figure 4 This is a schematic diagram of time slot merging;

[0050] Figure 5 This is a schematic diagram of advance scheduling based on strict priority.

[0051] Figure 6 This is a flowchart of the advance scheduling process based on strict priority.

[0052] Figure 7 This is a schematic diagram of end-to-end delay optimization based on local time slot search;

[0053] Figure 8 This is a flowchart of end-to-end delay optimization based on local time slot search;

[0054] Figure 9 Optimize the output algorithm graph for the gated list;

[0055] Figure 10 This is a network topology diagram for Example 1;

[0056] Figure 11 This is a schematic representation of the initial time slot occupancy in Example 1;

[0057] Figure 12 This is a schematic diagram of the optimized time slot occupancy in Example 1. Detailed Implementation

[0058] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0059] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures, and should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0060] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0061] This invention provides a scheduling method for event-triggered flows in time-sensitive networks, involving parameters as shown in Table 1:

[0062] Table 1

[0063]

[0064] In this time-sensitive network, the following constraints apply:

[0065] Network constraints:

[0066] The entire network is a single-path, loop-free network, and a link variable is defined. Indicates TT stream Whether it passes through the link from node m to node n; if so, then... If not passed Excluding the source and destination nodes in the network, all remaining nodes need to achieve fully reliable transmission with a packet loss rate of 0, meaning the inflow of traffic equals the outflow of traffic.

[0067]

[0068] For the source node, since all traffic originates from the source node, the following conditions must be met:

[0069]

[0070] For the destination node, all traffic is received from the destination node, and the destination node does not send traffic. Therefore, the following conditions must be met:

[0071]

[0072] Flow constraints:

[0073] TT streams are time-triggered streams and are sent periodically. This requires... Transmission time from m to n It must be greater than 0, and requires... The transmission is completed within its cycle, that is:

[0074]

[0075]

[0076] Time slot occupancy constraints:

[0077] During the transmission of TT streams on a switch, only one TT stream can be transmitted at a time, and only one TT stream can occupy the same time slot within the same period. Define a time slot occupancy variable. This represents the TT flow on the link from node m to node n. During the comprehensive scheduling period T A The occupancy status of the i-th time slot resource, if If this time slot is occupied, then Otherwise, it is 0. Therefore, on the link from node m to node n, the port time slot occupancy constraints of the same switch are as follows:

[0078]

[0079]

[0080] Time slot optimization constraints:

[0081] To determine whether a TT flow can be optimized, two conditions must be met: ① TT flow Current end-to-end delay Whether the delay is greater than the transmission delay, i.e., whether queuing delay occurred during transmission:

[0082]

[0083] ② Are there enough spare time slots for TT flow to adjust, reduce queuing delay, and thus reduce end-to-end delay?

[0084] Where a is the timeslot from which the TT stream is sent from the source node, and b is the timeslot from which the destination node receives the TT stream:

[0085]

[0086] Constraints on the number of time-aware shapers:

[0087] In a comprehensive scheduling cycle T A In, each TT stream The number of data frames sent is N iFor each data frame transmission, there is a time-aware shaper operation. A time-aware shaper event is defined as consisting of opening time, time slot transmission time, and closing time. Each time-aware shaper operation consumes an opening time Δ and a closing time Δ, such as... Figure 3 As shown. Therefore, in order to reduce system resource consumption and improve bandwidth utilization, multiple time slots of continuous transmission can be merged to reduce the number of time-aware shapers.

[0088] For two TT traffic streams with the same priority that are adjacent transmissions on the same link within the same scheduling period:

[0089]

[0090] Or, within the same scheduling period, adjacent unoccupied time slots on the same link:

[0091]

[0092] For those that meet the above conditions, the two time-aware shapers can be merged, such as... Figure 4 As shown.

[0093] This method includes the following three stages:

[0094] Phase 1: Obtain information such as the period, packet size, and priority of all TT flows from the switch, and calculate the overall scheduling period T. A The basic unit of time-slot transmission, the Slot, is determined by priority. Sort the TT streams and schedule them in order. High-TRT streams are allocated corresponding time slots according to their path order, such as... Figure 5-6 As shown, the specific steps include:

[0095] Step 1-1: Read all the information in the existing network and collect information on all TT streams in the current network;

[0096] Step 1-2: Sort all TT streams in descending order of priority, and calculate the overall scheduling period T of the TT streams. A And calculate each TT stream Relative to the comprehensive scheduling period T A The number of transmission frames N i And the basic unit for calculating time slot transmission, the slot;

[0097] The overall scheduling period is determined by the periods of all TT flows. The overall scheduling period takes into account the transmission time of all TT flows on every link in the entire network, ensuring that the flows reach the receiver before the worst-case latency. Therefore, the overall scheduling period T... ADefined as the least common multiple (LCM) of all TT flow cycles, where T i Indicates TT stream The period of is calculated using the following formula:

[0098] T A =LCM(T1,T2,…,T) i )

[0099] By comprehensively calculating the scheduling period, it can be determined that the TT stream needs to be sent multiple times within the scheduling period, and the time-triggered stream... The number of transmission frames within this comprehensive scheduling cycle is N. i :

[0100]

[0101] Based on the switch port transmission speed SP s and TT stream Data frame size Calculate Required time slot size

[0102]

[0103] Based on the time slot size required for each TT stream transmission, the basic unit of time slot transmission, the Slot, is calculated. A Slot is defined as all... The greatest common divisor (GCD) of the time slot size required for transmission is calculated as follows:

[0104]

[0105] Steps 1-3: Select the first TT stream And select the first link of the TT stream according to the path. Determine the link Is it equal to 1 (if it is 1, it means the current time slot is occupied)? If it is not equal to 1, it means the next transmission slot is occupied? Required time slots And Set to 1; if the current time slot Then skip the current time slot and select the next time slot. And repeat steps 1-3;

[0106] Steps 1-4: N i =N i -1, determine N i Is N ≠ 0? iIf the time slot is not equal to 0, then the time slot will be... Occupy, make And make N i =N i -1, repeat steps 1-4 until N. i =0;

[0107] Steps 1-5: Determine if this is the TT stream. Have all time slots been allocated for all the links traversed? If not, select the next link.

[0108] Steps 1-6: Determine if all TT streams have been scheduled. If not, select the next TT stream and proceed to Steps 1-3.

[0109] Steps 1-7: Output the preliminary time slot occupancy table.

[0110] Phase Two: After the initial allocation of time slots for all TT streams, the second phase of scheduling attempts to reduce the end-to-end latency of the TT streams through local time slot search, such as... Figure 7-8 As shown.

[0111] Step 2-1: Read the time slot occupancy table generated after advance scheduling and select the first TT stream. Select the link closest to the destination node;

[0112] Step 2-2: Start from the lowest priority TT stream Start searching, select On the link closest to the destination node, select The time slot. Search backwards from that time slot to determine... In adjacent links Is there an available time slot? If there is one, proceed to step three; otherwise, select the next link. After determining the link, select the next TT flow.

[0113] Steps 2-3: Determine if it is possible to... In the link The time slot occupied is moved forward, and then it is determined whether the move can reduce the time slot. If there is end-to-end delay, the spare time slots are eliminated by shifting the time slot occupancy and the link time slot occupancy table is updated. If the end-to-end delay cannot be reduced, the next link is selected.

[0114] Steps 2-4: Check if all TT streams have been optimized. If all have been optimized, generate the optimized time slot occupancy table.

[0115] Phase 3: Based on the optimized time slot allocation table, minimize the number of door openings and generate a corresponding door control list, such as... Figure 9 As shown, it includes the following steps.

[0116] Step 3-1: Read the optimized time slot occupancy table generated after time slot occupancy optimization, and select the time slot occupancy table of the first link;

[0117] Step 3-2: Select the first time slot of the link and determine... Is it equal to 1? If so... and Then determine if the priorities of the TT streams occupying these two time slots are equal. If they are equal, merge the two time slots; otherwise, select the next time slot. and Then the two unoccupied time slots will be merged; this process continues until the last time slot of the current link is reached.

[0118] Step 3-3: Select the first time slot of the link and determine... Is it equal to 1? If so... Then the gate list parameters are generated, and the gate priority parameter is... The binary number, according to Slot i The size of the time slot determines the time slot parameters; if Then set the gating priority parameter to all 1s, according to the Slot. i The time slot size determines the time slot parameters; this process continues until the last time slot of the current link is reached.

[0119] Step 3-4: Check if gating lists have been generated for all links. If gating lists have been generated for all links, output the generated gating lists. If there are still links for which gating lists have not been generated, select those links and repeat steps 3-2 to 3-3.

[0120] Example 1:

[0121] In such Figure 10 In the network topology diagram, the network consists of two source nodes, two destination nodes, and two TSN switches. The port transmission speed of the switches is SP. s The bandwidth is 100Mbps, and there are 3 TT streams in the entire network. The specific information is shown in Table 2.

[0122] Table 2

[0123]

[0124] Figure 11The initial scheduling process is shown. This link slot occupancy table includes all the links that TT streams must traverse from the source node to the destination node, described in square brackets, such as [Source Node 1, TSN Switch 1] and [TSN Switch 1, TSN Switch 2]. The horizontal axis represents time. This slot occupancy table is created by allocating frames sent by TT streams to the links pointing to their destinations, but in reality, it represents the time slots used for sending on the occupied ports.

[0125] Based on the scheduling algorithm for the initial time slot occupancy, the highest priority TT stream is selected. To begin. Therefore, first take the TT stream. It also occupies the link from source node 1 to TSN switch 1, i.e., [source node 1, TSN switch 1], [TSN switch 1, TSN switch 2], and [TSN switch 2, destination node 1]. TT flow The occupied link time slot is represented by a block, the length of which corresponds to the time slot required for transmission: Slot1 = 125 × 8 bits / 100 Mbps = 10 μs.

[0126] Next, the TT stream with priority 6 will be... The link required to reach its destination node is allocated, with a length corresponding to the transmission time slot Slot4 = 375 × 8 bits / 100 Mbps = 30 μs. Next, the TT stream of priority 5... The link required to reach the destination node is allocated, with a length corresponding to the transmission time slot Slot3 = 250 × 8 bits / 100 Mbps = 20 μs. Finally, the TT stream with priority 4 is... The link allocated to it to reach the destination node has a length corresponding to the time slot required for transmission: Slot2 = 125 × 8 bits / 100 Mbps = 10 μs.

[0127] The final preliminary time slot occupancy table is as follows: Figure 11 As shown, the TT stream can be seen. The delay occurred at TSN switch 1 due to the TT flow. Upon arrival at TSN switch 1, TSN switch 1 is transmitting a TT stream to destination node 2.

[0128] Figure 12 The process of the time slot optimization section is shown. The link time slot occupancy table includes the time slot occupancy of all TT streams after the initial scheduling.

[0129] Based on the time slot occupancy optimization algorithm, the highest priority TT stream is selected. Start optimizing. First, retrieve the TT stream. The link from the source node to the destination node is: [Source node 3, TSN switch 1], [TSN switch 1, destination node 2]. If there are no idle time slots during the transmission process, the next TT stream will be selected for optimization.

[0130] Next, select the TT stream with priority 6. Optimize, The link from the source node to the destination node is: [Source Node 2, TSN Switch 2], [TSN Switch 2, Destination Node 1]. If there are no idle time slots during the transmission process, the next TT stream will be selected for optimization.

[0131] Then select the TT stream with priority 5. Optimize, The links from the source node to the destination node are: [Source Node 2, TSN Switch 2], [TSN Switch 2, TSN Switch 1], [TSN Switch 1, Destination Node 2]. During transmission, if there are idle time slots between the links [TSN switch 2, TSN switch 1] and [TSN switch 1, destination node 2], then mobile transmission is selected. Eliminate idle time slots on [TSN Switch 2, TSN Switch 1]. Similarly, after optimizing this link, the same applies to the link [Source Node 2, TSN Switch 2].

[0132] The final optimized time slot occupancy table is as follows: Figure 12 As shown, comparing the preliminary time slot occupancy table, we can see that the TT stream... The end-to-end latency was reduced by 20 μs due to optimization.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An end-to-end low latency scheduling method for time sensitive network time triggered flows, characterized in that: The method comprises the following steps: S1: obtaining information of all TT flows of the switch, and performing time slot allocation for all links through which all TT flows pass from the source node to the destination node according to the priority size; step S1 specifically comprises: S11: reading and collecting information of all TT flows in the network, including the period, message size and priority information of the TT flow; S12: all TT flows are sorted according to priority from high to low, and the integrated scheduling period of TT flows is calculated , and the number of transmission frames of each TT flow relative to the integrated scheduling period is calculated , and the time slot transmission basic unit is calculated; S13: Select the first TT stream And select the first link for the TT stream according to the path. Determine the occupancy variable of the i-th time slot of the link from node m to node n. If the value is not equal to 1, then the next transmission will be occupied. Required time slots and will Set to 1; if the current time slot =1 means the current time slot is occupied. Skip the current time slot and select the next time slot. And repeat step S13; S14: Let = -1, determine whether ≠0, if ≠0, then add the period of to the slot occupancy time and occupy again, i.e. , where denotes the slot after the slot length of slot i, repeat step S14 until =0; S15: judging whether the TT flow whether all the time slots of all the links passed have been allocated, if not, selecting the next link; S16: judging whether all TT flows have been scheduled, if not, selecting the next TT flow to enter step S13 again; S17: obtaining and outputting the preliminary time slot occupation table through steps S11-S16; S2: reducing the end-to-end delay of the TT flow through local time slot search; the step S2 of reducing the end-to-end delay of the TT flow through local time slot search specifically comprises: S21 : reading the preliminary time slot occupancy table, selecting a first TT flow selecting the link closest to the destination node; S22: From the lowest priority TT flow Start searching, select TT flow on the link close to the destination node The ith time slot occupation variable from node m to node n =1, search backward from this time slot, determine On the adjacent link If there is a free time slot, i.e. TT flow The ith time slot occupation variable from node n to node o =0, if there is, go to step S23, if not, select the next link, after the link is determined, select the next TT flow; S23: judging whether the time slot occupied on the link can be moved backward, then judging whether the end-to-end delay can be reduced after the movement, if yes, eliminating the idle time slot by the movement of the time slot occupation, and updating the time slot occupation table, if not, selecting the next link; S23: judging whether the time slot occupied on the link can be moved backward, then judging whether the end-to-end delay can be reduced after the movement, if yes, eliminating the idle time slot by the movement of the time slot occupation, and updating the time slot occupation table, if not, selecting the next link; S23: judging whether the time slot occupied on the link can be moved backward, then judging whether the end-to-end delay can be reduced after the movement, if yes S24: checking whether all TT flows have been optimized, if all have been optimized, generating the time slot occupation table after optimization; S3: according to the optimized time slot occupation table, reducing the number of time-aware shapers and the number of opening doors as much as possible, and generating the corresponding door list.

2. The method of claim 1, wherein: The integrated scheduling period in step S12 is: wherein denotes the least common multiple, the period of The number of TT streams with respect to the integrated scheduling period The number of transmission frames is calculated as: The time slot transmission basic unit Is: wherein denotes the greatest common divisor, denotes the TT flow Required slot size: wherein represents the switch port sending speed, represents the TT flow data frame size.

3. The method of claim 1, wherein: Step S3 specifically comprises: S31: reading the time slot occupation table generated after the time slot occupation optimization, and selecting the time slot occupation table of the first link; S32: select the first time slot of the link, judge whether it is equal to 1, if =1, and =1, judge whether the TT flow priorities occupying the two time slots are equal, if equal, merge the two time slots, if not equal, select the next time slot; if =0, and =0, merge the two unoccupied time slots; keep looping until the last time slot of the current link; S33: select the first time slot of the link, judge whether equal to 1, if =1, then generate the gating list parameter, the gating priority parameter is the binary number of the time slot, determine the time slot parameter according to the time slot size; if =0, then set the gating priority parameter as all 1, determine the time slot parameter according to the time slot size; loop until the last time slot of the current link; S34: checking whether all links have generated the door list, if all have generated the door list, outputting the generated door list, if there is still a link without generating the door list, selecting the link to repeat steps S32-S33.

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