Simple Precision Time Protocol at Meta

This post introduces Simple Precision Time Protocol (SPTP), a simplified version of PTPv2 designed for Meta's data center deployments. SPTP reduces network communication and state machine complexity compared to standard PTPv2, leading to significant improvements in CPU, memory, and network utilization. It achieves this by reducing the number of packet exchanges to three (delay request, sync, followup/announce) and eliminating the need for persistent state on clients and servers. The post also details SPTP's reliability mechanisms, including multi-clock reliance and a clock ensemble approach using Chauvenet's criterion for outlier rejection and weighted averaging to ensure accurate timing information.