Enhanced PTP User Guide (UG1602)

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1.1 English

sfptpd provides a simple clustering algorithm to select between sync instances using a discriminator mode. In this mode a passive sync instance (for example NTP) is designated as the discriminator between multiple active sync instances (such as PTP). Any wildly divergent time sources are excluded from the sync instance selection.

Note: While similar to the sfptpd Best Master Clock (BMC) Discriminator feature this operates between sync instances (on separate PTP domains and/or interfaces) rather than within a PTP domain and is a preferable solution because full clock reconstruction is continuously performed for each candidate source.

For example the following configuration prefers sync instances that are within 100 ms (100000000 ns) of an NTP reference, the sync instance for which is named ntp1:

clustering discriminator ntp1 100000000 1

See Configuration Options for a complete description of the clustering option.

Future releases might provide further modes of clustering beyond a discriminator.