Configuring the PTP Service
You can use the pmc command to query the status of ptp4l
operation. The following example shows the results of running pmc on a slave clock system that's directly connected to the grandmaster clock system without any intermediate boundary clocks:
sudo pmc -u -b 0 'GET TIME_STATUS_NP'
sending: GET TIME_STATUS_NP
080027.fffe.7f327b-0 seq 0 RESPONSE MANAGEMENT TIME_STATUS_NP
master_offset -98434
ingress_time 1412169090025854874
cumulativeScaledRateOffset +1.000000000
scaledLastGmPhaseChange 0
gmTimeBaseIndicator 0
lastGmPhaseChange 0x0000'0000000000000000.0000
gmPresent true
gmIdentity 080027.fffe.d9e453
sudo pmc -u -b 0 'GET CURRENT_DATA_SET'
sending: GET CURRENT_DATA_SET
080027.fffe.7f327b-0 seq 0 RESPONSE MANAGEMENT CURRENT_DATA_SET
stepsRemoved 1
offsetFromMaster 42787.0
meanPathDelay 289207.0
This output examples include the following useful information:
-
gmIdentity
-
The unique identifier of the grandmaster clock, which is based on the MAC address of its network interface.
-
gmPresent
-
Whether an external grandmaster clock is available. This value is displayed as
false
on the grandmaster clock itself. -
meanPathDelay
-
An estimate of how many nanoseconds by which synchronization messages are delayed.
-
offsetFromMaster
-
The most recent measurement of the time difference in nanoseconds relative to the grandmaster clock.
-
stepsRemoved
-
The number of network steps between this system and the grandmaster clock.
For more information, see the phc2sys(8)
, pmc(8)
, and ptp4l(8)
manual pages, and IEEE 1588.