| With the development of network technology,Ethernet is widely used in the fields of automation industry,intelligent driving and aerospace.Compared with traditional Ethernet,the deterministic network has developed a time-sensitive network standard protocol,and defined key technologies such as time synchronization,low bounded delay and high reliability in the network.This enables the deterministic network to provide deterministic transmission with low latency and low packet loss rate on the basis of completing the switching transmission function,which is more popular in the field with high requirements for the certainty of transmission service delay.The research of the thesis comes from the major technical research project of national ministries and commissions.This thesis introduces the scheduling mechanism in the protocol by studying the Qav protocol,Qbv protocol and Qch protocol related to the scheduling technology.After analyzing the deterministic network application scenario,the logic circuit is designed by combining the protocol standard and scheduling algorithm,and the realization of the TSN scheduling system is completed based on this.The scheduling system designed in this thesis transmits data in the form of pipeline,and each module completes the functions of time synchronization,information reporting and configuration,data frame forwarding,data scheduling and system work monitoring in sequence.By designing local information updating and switching module,the scheduling system can receive configuration messages related to forwarding and scheduling to control system scheduling,and can periodically report the local information collected from each sub-module.Since the data frame of the deterministic network adopts the 802.1Q format,data frame parsing and switching module designed in this thesis can complete the 802.1Q data frame transmission and is compatible with the traditional Ethernet data frame transmission.Data frame parsing and switching module performs priority regeneration and data frame information extraction for different types of data streams through 802.1Q tags,thereby dividing the data streams in the application scenario into four categories: TS streams,TSN streams,SR streams,and BE streams for processing.In the realization of the data scheduling function,which is mainly studied in this thesis,the queue cache scheduling module is implemented in the form of separate scheduling of data frame and data frame information,and the design and implementation of the scheduling mechanism model are completed in the queue scheduling module.In order to make the scheduling priority,transmission bandwidth and delay of various types of data flexibly configured according to the scenario requirements to complete deterministic transmission,the queue scheduling module adopts the TAS mechanism based on gate control.The queue scheduling module also adds the CQF mechanism,so that the TS data stream can be transmitted within the time slot period configured by the user,thereby ensuring the deterministic transmission of the most important TS stream in the transmission application with bounded low delay.In addition,in response to the problem that the transmission of low-priority data streams is stagnant and affects the quality of service when TSN flow and SR flow data bursts,the queue scheduling module uses the CBS mechanism to perform traffic shaping on the bandwidth reservation flow in the scheduling system.Since the parameter settings in the CBS mechanism are affected by the transmission of other types of data streams,the actual bandwidth of the data stream will deviate from the predetermined value,so this thesis also adds the token bucket mechanism to limit the bandwidth.Finally,this thesis designs a simulation verification platform to verify the correctness of each function of the scheduling system,and then builds a test platform for functional and performance testing and simulation testing of actual application scenarios.The TSN scheduling prototype verification platform is implemented by XCVU13 P,using 56160 LUTs,79001 FFs,7749 LUTRAMs and 845 BRAMs.Based on the TSN scheduling prototype verification platform,the scheduling system designed in this thesis can complete the priority scheduling and transmission of various data streams,and the total data stream processing bandwidth reaches 10 Gbps,the traffic shaping and bandwidth limiting functions of bandwidth reservation streams work effectively,and the packet loss rate of other types of data streams is 0%,which proves that the system is reliable in data transmission.When simulating the actual application scenario test,various data streams generate burst transmissions,and the transmission of TS streams in the scheduling system is not affected by other data streams,and can be completed within the configured delay limit.And the minimum transmission delay boundary that the scheduling system can complete is 2.5 μs,indicating that the scheduling system has the deterministic transmission function with bounded low delay.The scheduling system designed in this thesis has completed the design goal. |
