Research Of TT Service Switching And Synchronization Technology On Deterministic Ethernet

With the rapid development of science and technology,there have been more and more requirements for the service transmission characteristics of real-time and security fault tolerance in the aerospace,rail transportation and high level industrial control filelds.The best-effort delivery service provided by traditional Ethernet cannot meet the demand obviously.Deterministic Ethernet introduces two key technologies,clock synchronization and time triggering,based on traditional Ethernet,so that the network has real-time,secure and fault-tolerant communication capabilities,which solves the problem of high real-time and high-security service transmission effectively.Relying on the scientific research project"Design and Implementation of Deterministic Ethernet Switches",we focus on two key technologies of deterministic switching networks in this thesis.One is high-precision clock synchronization technology based on SAE AS6802 protocol,and the other is time-trigger service switching technology.First of all,we briefly introduce the research background and basic concepts of Deterministic Ethernet in this thesis.Secondly,by analyzing the system composition and working principle of Deterministic Ethernet,we show that SAE AS6802 clock synchronization technology and TT service switching technology are the two key technologies of the network.And then,according to the functional requirements of the deterministic switching unit,the overall structure of the switching unit supporting clock synchronization and TT service switching has been designed and implemented,and the details of key sub-modules such as input shunting,clock synchronization,TT service switching,and output arbitration have been explained.,At the same time,we describe the technical advantages of self-developed clock synchronization module and TT service switching module.Next,we verify the correctness and reliability of the functions of the key sub-modules through the simulation platform.Finally,based on the actual network parameters,a board-level test platform has been built.The synchronization precision of the platform is less than 100ns.Meanwhile,it can complete the TT service switching transmission without conflicts and with minimal transmission delay and delay jitter according to the time schedule.We propose four innovations in this thesis.First,a synchronization unit with integrated CM and SC functional models has been designed to solve the problem of cascading synchronization between switching nodes in a complex network.Second,a pre-integration strategy has been used between the permanence function and the compression function to pre-group the permanence points,which reduces the delay in compressing the permanence points of the compression function,accelerates the processing speed of the compression function,and improves synchronization efficiency.Third,the scheduling module reads the scheduling information through a pre-reading strategy to ensure that the scheduling module always pre-stores the next scheduling information,solving the problem of low efficiency of TT service switching due to the slow reading of scheduling information.Fourth,we make the input port set the receiving window to police the TT service and the output port send the TT service regularly,the input and output schedules combined and shared,which fixes the switching delay of the TT service.