Virtual Token And Ethernet-based Real-time Network Protocol Research

With the development of computer technology,the requirement of real-time quality of computer network is getting higher and higher in various kinds of application fields from academy to industry. The Ethernet which is used widely at present is a typical non-real-time network because of access conflict that leads uncertain data transmission time. If we want to realize real-time application in the current software and hardware environment of Ethernet,we must solve the question of access conflict. Real-time high-speed data transmission on network can be achieved not only through improving hardware,but also through designing application-specific network protocol based on current hardware level.This paper designs a application-specific real-time protocol based on virtual token and Ethernet,which is based on Ethernet data-frame protocol and uses idea of token bus network. This protocol is based on current hardware foundation of Ethernet and solves access conflict through token-control by creating virtual token on application layer. At the same time,according to the special network communication requirement of real-time computing system,the proposed protocol takes advantage of TCP and UDP protocols,and introduces token-control,incorporate with network management measures such as multi-layer error control,master-slave broadcasting,non-equality net accessing,etc. All these make Ethernet a logical real-time network.This protocol provides a transparent data transmit system for the software of upper level application. The structure of the system can be adjusted dynamically. The more important is that it makes full use of network bandwidth. It controls the use of network resource through token-control,decreases resource waste causing by access conflict in Ethernet communication and achieves high-speed real-time data transmission.