NTP vs PTP: when to choose which protocol?

NTP and PTP both keep the clocks and devices on a network showing the same time. The difference is precision and price. NTP is accurate to the millisecond and runs on ordinary network hardware. PTP is a thousand times more precise, down to a fraction of a millionth of a second, but it needs special network switches and therefore a larger investment.

Which one do you need?

• Servers, computers, clocks in buildings, log files: NTP is more than enough.
• Television broadcasts, financial trading, high-voltage substations, 5G networks: here PTP is required, because "almost equal" is not good enough.

In short

Are milliseconds good enough? NTP. Do you need microseconds or better? PTP. In most cases NTP is the right answer, and we will tell you so honestly. In doubt? We are happy to think along with you.

NTP and PTP do the same thing on the surface: synchronise clocks across a network. In practice they differ by three orders of magnitude in accuracy, and the question "which one do we pick" becomes an investment decision worth thousands of euros in difference.

What is the core difference between NTP and PTP?

	NTP	PTP (IEEE 1588)
Typical LAN accuracy	1–10 ms	100 ns – 1 μs
Extra hardware required	no	yes (PTP-aware switches)
Complexity	low	high
Infrastructure cost	small	substantial
Use case	servers, clocks, IT logs	broadcast frame sync, financial trading, digital substations

## Why is PTP so much more accurate?

NTP passes through switches and routers, and every hop adds unpredictable delay. PTP uses boundary clocks and transparent clocks, switches that actively update the timestamp while the packet passes through their queue. On top of that PTP places its timestamps in hardware (NIC level), not in software OS level like NTP does. That removes every source of jitter from the chain.

When is NTP enough?

• IT servers and logging: millisecond sync is more than sufficient. An NTP100-GNSS comfortably serves a data centre.
• Clocks in public spaces and broadcast studios: NTDS-series NTP clocks are frame-accurate (a 40 ms tolerance is well over one frame).
• Hospitals, schools, office environments: NTP is fine with PoE clocks.

When do you really need PTP?

• Financial trading (MiFID II, FINRA Rule 7430): 100 μs required between trading-platform events. Calls for a PTP grandmaster.
• Digital substations (IEC 61850-9-3): protection relays must be synchronised within a few microseconds for differential protection. Calls for PTP Power Profile.
• 5G fronthaul (3GPP/O-RAN): telecom requirements of ±1.5 μs at the cell level. Calls for PTP G.8275.
• Frame-accurate live broadcast: sub-frame sync across more than one studio or vehicle. Often a combination of PTP plus SMPTE Time Code.
• High-frequency trading: nanosecond budget across the entire chain.

Can you combine NTP and PTP on one network?

In practice both protocols often run side by side: PTP for the mission-critical equipment on a separate PTP-aware switch tree, NTP for everything else. A Masterclock GMR6000 can serve as both at once, PTP Grandmaster plus NTP Server in a single box.

In practice via Daylight

Most customers ask for NTP and that is what they actually need, no more, no less. For the specific cases where PTP is unavoidable, we know which switches you need and which pitfalls to watch out for. Call or email Daylight for independent advice tailored to your scale.

Sources

• IEEE 1588-2019 — Precision Time Protocol
• RFC 5905 — NTPv4
• IEC 61850-9-3 Power Profile (for digital substations)

Sources and standards

This page references the following official standards and authoritative bodies:

1. IETF RFC 5905 — Network Time Protocol Version 4: Protocol and Algorithms Specification 2. IEEE 1588-2019 — Standard for a Precision Clock Synchronization Protocol 3. NIST Time and Frequency Division — Time Services overview