Ethernet-based bus systems facilitate continuous communication between automation levels. An increasing number of companies use Ethernet-based bus systems instead of first-generation fieldbuses. Not only demanding environmental conditions, but also high demands on the fault tolerance of the network, e.g. as in safety-critical applications requiring a discussion of the topic of reliable operation of Ethernet-based bus systems in industrial automation. With the help of the standard, planners and operators of an Ethernet-based communication network for industrial applications as well as installers and maintenance personnel will be given the opportunity to observe all measures to enable the reliable operation of such a communication system. The outline follows the lifecycle model: 1. conceive; 2. design; 3. realise; 4. launch; 5. service. The user of this standard is accompanied in all phases of network construction and network operation. In addition, an overview of relevant standards and sources of further information is given. The standard assists the user in terms of these aspects. It deliberately does not address specific application protocols, but the content focus is on Ethernet in accordance with IEEE 802.3 and switching according to IEEE 802.1, or bridge functionality of real-time Ethernet variants according to IEC 61158-3 and -4 and redundancy functionality according to DIN EN 62439.