White Rabbit: Sub-nanosecond timing over Ethernet

The White Rabbit (WR) project is a multi-laboratory, multi-company effort to bring the best of the data transfer and the timing world together in a completely open design. WR is a fully deterministic Ethernet-based network for general purpose data transfer and synchronization. The aim is to enable the synchronization of a large number of nodes with sub-nanosecond accuracy and picosecond jitter over long lengths of fibre. The key technologies used are physical layer syntonization (clock recovery) and the Precision Time Protocol (IEEE 1588). WR generates sub-nanosecond synchronous precision timing in all nodes by continuous tracking and compensating the transmission delays. We give an overview of the WR project and describe the design goals and specifications of the project. The WR switch and the (user) node which are the central components of the WR system and real timing measurements of prototypes of WR hardware are presented.