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16.4. Using the PTP Management Client

The PTP management client, pmc, can be used to obtain additional information from ptp4l as follows:
~]# pmc -u -b 0 'GET CURRENT_DATA_SET'
        90e2ba.fffe.20c7f8-0 seq 0 RESPONSE MANAGMENT CURRENT_DATA_SET
                stepsRemoved        1
                offsetFromMaster  -142.0
                meanPathDelay     9310.0
~]# pmc -u -b 0 'GET TIME_STATUS_NP'
        90e2ba.fffe.20c7f8-0 seq 0 RESPONSE MANAGMENT TIME_STATUS_NP
                master_offset              310
                ingress_time               1361545089345029441
                cumulativeScaledRateOffset   +1.000000000
                scaledLastGmPhaseChange    0
                gmTimeBaseIndicator        0
                lastGmPhaseChange          0x0000'0000000000000000.0000
                gmPresent                  true
                gmIdentity                 00a069.fffe.0b552d
Setting the -b option to zero limits the boundary to the locally running ptp4l instance. A larger boundary value will retrieve the information also from PTP nodes further from the local clock. The retrievable information includes:
  • stepsRemoved is the number of communication paths to the grandmaster clock.
  • offsetFromMaster and master_offset is the last measured offset of the clock from the master in nanoseconds.
  • meanPathDelay is the estimated delay of the synchronization messages sent from the master in nanoseconds.
  • if gmPresent is true, the PTP clock is synchronized to a master, the local clock is not the grandmaster clock.
  • gmIdentity is the grandmaster's identity.
For a full list of pmc commands, type the following as root:
~]# pmc help
Additional information is available in the pmc(8) man page.