Understanding sfptpd Output

Enhanced PTP User Guide (UG1602)

Document ID
UG1602
Release Date
2022-10-18
Revision
1.0 English

Once it has reached a SLAVE state, sfptpd generates output describing the current state of the synchronization.

By default sfptpd will output the offset data to stdout. You can redirect stats_log output to file using the configuration file stats_log parameter.

When logging the stats_log to file, it is possible to override this using the -v option on the sfptpd command line to cause stats to display on stdout.

The following examples are from a PTP sync module on a slave server. The timestamp at the start of the line has been omitted. Other sync modules produce similar output.

[ptp1:gm->phc0(enp1s0f0)], offset: 0.500, freq-adj: -663.353, in-sync: 1,
one-way-delay: 7534.500, grandmaster-id: 00a0:69ff:fe0c:2eb5
[phc0(enp1s0f0/enp1s0f1)->system], offset: 2.812, freq-adj: 46378.715,
in-sync: 1
Table 1. sfptpd Offset Output
Parameter Description
[ptp1:gm-> phc0(enp1s0f0)]

A line of output generated for measurements between the external master clock and the Local Reference Clock:

  • the -> separator indicates that the right-hand clock is being synchronized to the left-hand one
  • a -- separator indicates no synchronization between clocks
offset

The current offset (nanoseconds) between the master clock and the slave clock identified at the start of the line.

Immediately following startup this is expected to be a large value, but will gradually decrease until it settles to its lowest value. Synchronization can typically take between 15-30 minutes.

freq-adj The current rate (PPB) at which the clock is being disciplined by sfptpd. This value is stored in the freq-correction file for this clock every 60 seconds.
in-sync

The in-sync flag will be 1 when the offset between master and slave clocks is below the value of the local_sync_threshold option (default (hardware timestamping 1µs) for a period of 1 minute.

The local_sync_threshold when using software timestamping is 100µs.

The in-sync flag will be 0 before the above condition is true.

The in-sync flag will be 0 if the offset becomes greater than the local_sync_threshold.

The in-sync flag will change to 0 if an alarm condition exists on the server to indicate problems in the PTP network, such as PTP messages not being sent or received by the slave server.

Check the topology file for current alarms status.

one-way-delay

The current one-way-delay (nanoseconds) between master and slave servers.

This value should not be zero, but, once the server is synchronized, it should remain fairly stable:

  • If the value is zero, check that Delay_Req and Delay_Resp message are being sent and received.
  • If the value does not change at all over an extended period, check the Delay_Req interval.

Check the topology file for current alarms status.

parent-id UUID of the upstream master clock. This can be a boundary clock or the GM Master clock.
gm-id Master clock UUID derived from its MAC address.
[phc0(enp1s0f0/enp1s0f1)->system]

A line of output generated for measurements between the Local Reference Clock and the server system clock:

  • the -> separator indicates that the right-hand clock is being synchronized to the left-hand one
  • a -- separator indicates no synchronization between clocks