As the applications of real-time computing technology are becoming more and more popular in many safety critical domains such as avionics, national defense and transportation systems, field network faces new requirements and challenges because of the coexistence of different kinds of synchronous real-time, asynchronous real-time and non-real-time communication requirements. The realization approach and schedulability analysis of safety critical real-time network are very crucial because of giving a way to solve the problem. Firstly, the shortcomings of the existing COTS network such as Ethernet are described. And then, a high reliable and real time Ethernet communication protocol known as E&TTE (event- and time-triggered Ethernet) based on event- and time-triggered approach is presented. The E&TTE based real time network is flexible, and the communication time is predictable. At the same time, the network scheduling model is constructed, and the global schedulability analysis is done in this paper. The rationality and feasibility of E&TTE protocol is also proven by a concrete example. With E&TTE protocol, the diverse requirements of safety critical real time network can be met better. In addition, the E&TTE protocol can be widely applied to the field control network of ordinary industry systems.