Discipline & poll control
08A controlled loop adjusts both phase and frequency, while polling adapts measurement frequency to clock conditions.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 11.3 ↗
RFC 5905 · § 11.3EXAMPLE
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04
Close the measurement loop.
New accepted samples update the next estimate.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
Read the updated RFC section ↗
Steer a clock with feedback over time.
- The discipline combines phase-locked and frequency-locked control behavior.
- The clock-adjust process applies frequency correction and a fraction of remaining offset at regular intervals.
- The state machine treats startup, spikes, large offsets, and steady tracking differently; polling uses feedback and bounds.
An NTP implementation can step a large offset under defined conditions; it does not promise that time always moves smoothly. Leap processing and applications need to account for clock behavior.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
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