NTP (Network Time Protocol)
ntp
A networking protocol for clock synchronization between computer systems over packet-switched networks.
PTP (Precision Time Protocol)
ptp
Definition
PTP (Precision Time Protocol) is a network time synchronization protocol standardized as IEEE 1588. Where NTP provides millisecond-level accuracy, PTP leverages hardware timestamping to achieve microsecond-to-nanosecond synchronization. It is designed for LAN environments, and its precision depends heavily on hardware support in network switches and network interface cards.
Architecture
PTP uses a hierarchical structure headed by a Grandmaster Clock (GMC), which is typically connected to a GPS receiver or atomic clock. The GMC distributes precise time to all devices on the network. The Best Master Clock Algorithm (BMCA) automatically elects one clock from among multiple GMC candidates by comparing, in a fixed order, the priority values configured by the operator and the quality of each candidate's time source.
Use Cases
PTP is deployed in financial exchanges, 5G base station synchronization, broadcast audio/video alignment, power grid phase synchronization, and industrial control systems. The best-known requirement in finance is the EU's MiFID II regulation, which obliges firms engaged in high-frequency trading to keep their clocks within 100 microseconds of UTC and to record timestamps at a granularity of one microsecond or finer. For other forms of algorithmic trading the required granularity is one millisecond, so the bar differs by the style of trading. In cloud environments, AWS Amazon Time Sync Service supports PTP, enabling EC2 instances to achieve microsecond-level time synchronization.
Was this article helpful?
Related Terms
Stratum
stratum
Stratum is the designation for each level in NTP's hierarchical model, ranging from Stratum 0 (atomic clocks and GPS receivers) to Stratum 15, indicating distance from the reference time source.
Atomic Clock
atomic clock
An atomic clock measures time by using the quantum-mechanical transition frequency of atoms as its reference, achieving accuracies on the order of one second in hundreds of millions of years and forming the backbone of modern timekeeping.
Related Articles
How Time Zones Work - Understanding UTC Offsets and the Global Time System
Learn how time zones divide the world into regions with different local times, how UTC offsets work, and why some zones use half-hour increments.
Daylight Saving Time - How Clock Changes Affect Global Coordination
Understand how daylight saving time works, which countries observe it, when transitions occur, and how DST complicates international scheduling.
Unix Timestamps Explained - How Computers Represent Time as a Single Number
Learn what Unix timestamps are, why they count seconds from January 1, 1970, how to convert them to human-readable dates, and what the Year 2038 problem means.