White Rabbit: CERN's Open-Hardware Protocol for Sub-Nanosecond Network Sync

White Rabbit is an open hardware, firmware, and software project originating at CERN that extends Ethernet to deliver sub-nanosecond synchronization accuracy and picosecond-level precision across distributed systems. It is designed to scale to thousands of nodes separated by typical distances of around 10 km, while simultaneously carrying reliable gigabit-rate data over the same network.

The technology is aimed at large physics installations and similar environments where precise time-tagging of measurements and deterministic triggering are essential. Because the full stack is open and produced by multiple commercial vendors, users avoid lock-in while still getting industrial-grade hardware. CERN is actively hiring FPGA and hardware designers to advance the next generation of White Rabbit switches and ultra-low-jitter nodes, including an eRTM board with integrated jitter below 100 femtoseconds.