Filter noisy samples
06Each peer has a recent sample history. Delay ordering and uncertainty tracking reduce the influence of network jitter.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 10 ↗
RFC 5905 · § 10EXAMPLE
3 / 3
03
Describe the peer with uncertainty.
The next stage receives more than a single raw clock reading.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
RFC 1305 association timeout behaviorRFC 5905 §10
NTPv4 retains the last packet’s stratum and leap state. Aging uncertainty increases synchronization distance until the association is no longer fit for synchronization.
Read the updated RFC section ↗Filter each source before comparing sources.
- The filter retains the most recent sample tuples in an eight-stage history.
- Candidate samples are ordered by increasing delay and checked for freshness.
- Dispersion grows as measurements age; synchronization distance includes half the delay plus dispersion.
In NTPv4 an old association becomes unsuitable when its growing distance exceeds the threshold, rather than signaling timeout by rewriting its last stratum and leap fields.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
Privacy