Without precise specifications, Ethernet cannot satisfy real-time demands and efficiency requirements in automation engineering. Thus, appropriate transmission procedures must be defined which make Ethernet efficient and compatible with real-time requirements. The diversity of real-time Ethernet solutions available on the market does not make it easy to keep perspective. Even specialists sometimes find it difficult to fully evaluate and compare how different real-time Ethernet solutions work and what effects they produce. In the end, an objective comparison of the solutions can only be made when actual application scenarios are available. What is important is to understand the basic principles of different real-time Ethernet solutions and how they work.