Time-Triggered Network Traffic Scheduling Software

In the traditional Ethernet,if there are multiple applications on the same terminal need to send messages at the same time,competition will occur between link resources,resulting in an uncertain delay in the message transmission process.When a switch needs to send multiple messages to the same terminal at the same time,the messages need to be queued within the switch and then be sent in order.This will cause uncertainty in message transmission time.The time uncertainty of traditional Ethernet cannot meet the requirements of real-time systems which require real-time and time-deterministic message transmission.Time-Triggered Ethernet creatively adds the time-triggered concept on the basis of standard Ethernet.By using time division multiple access(TDMA)strategy and timetriggered scheduling algorithm,various time-triggered services are scheduled without conflicts.It can ensure the real-time feature of the network,and meet the real-time requirements of real-time transmission services.In this paper,the scheduling methond of periodic messages in Time-Triggered Ethernet(TTE)is studied,and the message scheduling algorithm and message scheduling software are proposed and implemented.Moreover,the upper-layer applications and device drivers for terminals in the Linux system are implemented.The main work of this thesis is summarized as follows:1)The model for network information and TT messages is established,and the algorithm of the message scheduling is proposed.The algorithm uses the maximum matching algorithm to prioritize TT messages,uses the Dijkstra algorithm to determine the message transmission path,and uses the "full path" scheduling strategy to determine message slot.The fragmentation of idle time slots is reduced,and the scheduling success rate of TT messages can be improved.2)Achived the message schedule software.The main features of the software are summarized as follows:(a)network information can be parsed from a local XML file or generated by time;(b)Run the message scheduling algorithm to get the message schedule and display it in the graphical interface;(c)Generate a message sending schedule and a receiving schedule for every network node;(d)Send the schedule to the node's software by using TCP protocol.3)The software of the network terminal is implemented,and the module of sending and receiving TT messages is added to the existing Ethernet node card driver.The terminal software configures the schedule table?the specific content of the TT frame and the other configuration information into the hardware through the driver.Fianaly,we complete the deterministic transmission and reception of the TT frame.4)The function of the scheduling software and terminal software is tested.The actual machine test was carried out to accomplish the deterministic sending and receiving of TT messages according to the schedule.