https://lesitedefrancois.be/en/tags/timing/Recent content in Timing on Le Site de FrançoisHugo -- gohugo.ioen© 2026 Françoishttps://lesitedefrancois.be/en/telco/ptp-precision-time-protocol/Mon, 01 Jan 0001 00:00:00 +0000https://lesitedefrancois.be/en/telco/ptp-precision-time-protocol/<p><strong>Precision Time Protocol (PTP)</strong>, standardised as <strong>IEEE 1588</strong>, distributes a common <strong>reference time</strong> across packet networks so that distributed nodes share a clock with <strong>sub-microsecond to nanosecond</strong> accuracy — far beyond what <strong>NTP</strong> typically achieves over IP. PTP operates in a <strong>master–slave hierarchy</strong>: a <strong>Grandmaster Clock (GM)</strong> holds traceability to <strong>GNSS</strong> (GPS, Galileo, etc.) or a <strong>Primary Reference Time Clock (PRTC)</strong>; <strong>Boundary Clocks (BC)</strong> terminate and regenerate timing on hops; <strong>Transparent Clocks (TC)</strong> correct residence time in switches without terminating the protocol. Messages (<strong>Sync</strong>, <strong>Follow_Up</strong>, <strong>Delay_Req/Resp</strong>, optional <strong>Announce</strong>) implement a <strong>delay request–response</strong> mechanism to estimate path asymmetry and offset each <strong>Ordinary Clock (OC)</strong> slave relative to the grandmaster.</p>