Using standard communication protocols for spacecraft communication links can provide interface compatibility between communication devices and components. Thus, it can improve the design and development process as well as integration and test activities at all levels and provide the potential of reusability across projects. The aim of this space engineering standard is to define the interface services and to specify their corresponding network protocol elements for spacecraft using the Time-Triggered Ethernet data network. It also aims at defining requirements for the harmonisation of the physical interfaces and usage of the [IEEE 802.3] and [SAE AS6802] layer features. This standard may be tailored for the specific characteristic and constraints of a space project in conformance with ECSS S ST 00. Approach The approach of the ECSS working group for defining this standard aims at identification of layers, services and functions of the typical Time-Triggered Ethernet communication network to ensure the use of the technology for various space projects. The standard aims at: -·ð Identifying Reference Architectures (Layers, Services, Functions and Elements of protocol) of typical Time-Triggered Ethernet communication network; -·ð Characterizing Services, Functions and Elements of Protocol of each Layer within identified Reference Architectures, using concrete project specifications; -·ð Define normative requirements rather than recommendations. As far as possible, the defined communication requirements are extracted from the experience on existing spacecraft specifications.