Methodology for block arrivals reports # Basics on Ethereum time deadlines # The Ethereum specification defines strict time deadlines on its consensus layer: The spec first defines epochs, which are 6.4 minutes long and are composed of 32 slots of 12 seconds each. Although not explicitly defined in the specification, each epoch is further split into three periods: Block composition and its propagation (0 - 4th second, red boxes in the plot below).
