ISO/IEC/IEEE 8802-1AS:2021/Amd 1:2025 PDF

Overview

ISO/IEC/IEEE 8802-1AS:2021/Amd 1:2025 is an amendment to the international standard (IEEE Std 802.1AS™) that governs timing and synchronization for time-sensitive applications in bridged local area networks (LANs). Published as IEEE Std 802.1ASdr‑2024 and adopted in the ISO/IEC/IEEE 8802 series, this amendment’s primary purpose is to update terminology to be inclusive, replacing legacy terms with alternatives identified by IEEE Std 1588g™‑2022. Figures and illustrations in the base standard are updated only to reflect the revised terminology.

Key topics and technical points

• Timing and synchronization for bridged LANs: The standard addresses mechanisms used to maintain synchronized time and frequency across bridged and switched Ethernet networks for time-sensitive applications.
• Terminology updates: Amendment 1 replaces prior terms with inclusive alternatives (aligned with IEEE 1588g‑2022). Changes are editorial in nature - no new protocol mechanics are introduced.
• PTP-related concepts referenced: Keywords and concepts retained or referenced include Grandmaster Clock, Grandmaster PTP Instance, PTP Relay Instance, PTP End Instance, phase offset, frequency offset, syntonization, and time-aware system.
• Synchronization objectives: Emphasis on accurate phase and frequency alignment (phase offset, frequency offset) and robust methods for clock distribution across network bridges and relays.
• Compatibility and update process: This amendment is a fast‑track adoption integrating IEEE editorial changes into the ISO/IEC/IEEE publication process.

Applications

• Time-sensitive networking (TSN) deployments requiring sub-microsecond or deterministic time alignment
• Industrial automation and control systems where coordinated timing is critical
• Professional audio/video and broadcast systems relying on synchronized media streams
• Telecommunications backhaul and distributed measurement systems
• Power systems and smart-grid devices that depend on precise timing for protection and monitoring

Who should use this standard

• Network architects and engineers designing TSN or PTP-based synchronization in bridged LANs
• Device and NIC manufacturers implementing IEEE 802.1AS timing functions
• System integrators and solution providers deploying time-aware networks
• Test labs, certification bodies, and standards compliance teams

Related standards

• IEEE Std 802.1AS™ (base timing and synchronization specification)
• IEEE Std 1588™ family (Precision Time Protocol) - specifically IEEE Std 1588g™‑2022 for terminology alignment
• Other parts of the ISO/IEC/IEEE 8802 series for LAN/MAN specifications

This amendment improves clarity and inclusivity in the standard’s language while preserving the original technical requirements for precise timing and synchronization in bridged local area networks.