23.6. Verifying Time Synchronization When PTP time synchronization is working properly, new messages with offsets and frequency adjustments will be printed periodically to the ptp4l and phc2sys (if hardware time stamping is used) outputs. These values will eventually converge after a short period of time. These messages can be seen in /var/log/messages file. An example of the ptp4l output follows: An example of the phc2sys output follows: For ptp4l there is also a directive, summary_interval , to reduce the output and print only statistics, as normally it will print a message every second or so. For example, to reduce the output to every 1024 seconds, add the following line to the /etc/ptp4l.conf file: An example of the ptp4l output, with summary_interval 6 , follows: To reduce the output from the phc2sys , it can be called it with the -u option as follows: Where summary-updates is the number of clock updates to include in summary statistics. An example follows:

Commands:
ptp4l[352.359]: selected /dev/ptp0 as PTP clock ptp4l[352.361]: port 1: INITIALIZING to LISTENING on INITIALIZE ptp4l[352.361]: port 0: INITIALIZING to LISTENING on INITIALIZE ptp4l[353.210]: port 1: new foreign master 00a069.fffe.0b552d-1 ptp4l[357.214]: selected best master clock 00a069.fffe.0b552d ptp4l[357.214]: port 1: LISTENING to UNCALIBRATED on RS_SLAVE ptp4l[359.224]: master offset 3304 s0 freq +0 path delay 9202 ptp4l[360.224]: master offset 3708 s1 freq -29492 path delay 9202 ptp4l[361.224]: master offset -3145 s2 freq -32637 path delay 9202 ptp4l[361.224]: port 1: UNCALIBRATED to SLAVE on MASTER_CLOCK_SELECTED ptp4l[362.223]: master offset -145 s2 freq -30580 path delay 9202 ptp4l[363.223]: master offset 1043 s2 freq -29436 path delay 8972 ptp4l[364.223]: master offset 266 s2 freq -29900 path delay 9153 ptp4l[365.223]: master offset 430 s2 freq -29656 path delay 9153 ptp4l[366.223]: master offset 615 s2 freq -29342 path delay 9169 ptp4l[367.222]: master offset -191 s2 freq -29964 path delay 9169 ptp4l[368.223]: master offset 466 s2 freq -29364 path delay 9170 ptp4l[369.235]: master offset 24 s2 freq -29666 path delay 9196 ptp4l[370.235]: master offset -375 s2 freq -30058 path delay 9238 ptp4l[371.235]: master offset 285 s2 freq -29511 path delay 9199 ptp4l[372.235]: master offset -78 s2 freq -29788 path delay 9204
phc2sys[526.527]: Waiting for ptp4l phc2sys[527.528]: Waiting for ptp4l phc2sys[528.528]: phc offset 55341 s0 freq +0 delay 2729 phc2sys[529.528]: phc offset 54658 s1 freq -37690 delay 2725 phc2sys[530.528]: phc offset 888 s2 freq -36802 delay 2756 phc2sys[531.528]: phc offset 1156 s2 freq -36268 delay 2766 phc2sys[532.528]: phc offset 411 s2 freq -36666 delay 2738 phc2sys[533.528]: phc offset -73 s2 freq -37026 delay 2764 phc2sys[534.528]: phc offset 39 s2 freq -36936 delay 2746 phc2sys[535.529]: phc offset 95 s2 freq -36869 delay 2733 phc2sys[536.529]: phc offset -359 s2 freq -37294 delay 2738 phc2sys[537.529]: phc offset -257 s2 freq -37300 delay 2753 phc2sys[538.529]: phc offset 119 s2 freq -37001 delay 2745 phc2sys[539.529]: phc offset 288 s2 freq -36796 delay 2766 phc2sys[540.529]: phc offset -149 s2 freq -37147 delay 2760 phc2sys[541.529]: phc offset -352 s2 freq -37395 delay 2771 phc2sys[542.529]: phc offset 166 s2 freq -36982 delay 2748 phc2sys[543.529]: phc offset 50 s2 freq -37048 delay 2756 phc2sys[544.530]: phc offset -31 s2 freq -37114 delay 2748 phc2sys[545.530]: phc offset -333 s2 freq -37426 delay 2747 phc2sys[546.530]: phc offset 194 s2 freq -36999 delay 2749
summary_interval 10
ptp4l: [615.253] selected /dev/ptp0 as PTP clock ptp4l: [615.255] port 1: INITIALIZING to LISTENING on INITIALIZE ptp4l: [615.255] port 0: INITIALIZING to LISTENING on INITIALIZE ptp4l: [615.564] port 1: new foreign master 00a069.fffe.0b552d-1 ptp4l: [619.574] selected best master clock 00a069.fffe.0b552d ptp4l: [619.574] port 1: LISTENING to UNCALIBRATED on RS_SLAVE ptp4l: [623.573] port 1: UNCALIBRATED to SLAVE on MASTER_CLOCK_SELECTED ptp4l: [684.649] rms 669 max 3691 freq -29383 +/- 3735 delay 9232 +/- 122 ptp4l: [748.724] rms 253 max 588 freq -29787 +/- 221 delay 9219 +/- 158 ptp4l: [812.793] rms 287 max 673 freq -29802 +/- 248 delay 9211 +/- 183 ptp4l: [876.853] rms 226 max 534 freq -29795 +/- 197 delay 9221 +/- 138 ptp4l: [940.925] rms 250 max 562 freq -29801 +/- 218 delay 9199 +/- 148 ptp4l: [1004.988] rms 226 max 525 freq -29802 +/- 196 delay 9228 +/- 143 ptp4l: [1069.065] rms 300 max 646 freq -29802 +/- 259 delay 9214 +/- 176 ptp4l: [1133.125] rms 226 max 505 freq -29792 +/- 197 delay 9225 +/- 159 ptp4l: [1197.185] rms 244 max 688 freq -29790 +/- 211 delay 9201 +/- 162
~]# phc2sys -u summary-updates
~]# phc2sys -s eth3 -w -m -u 60 phc2sys[700.948]: rms 1837 max 10123 freq -36474 +/- 4752 delay 2752 +/- 16 phc2sys[760.954]: rms 194 max 457 freq -37084 +/- 174 delay 2753 +/- 12 phc2sys[820.963]: rms 211 max 487 freq -37085 +/- 185 delay 2750 +/- 19 phc2sys[880.968]: rms 183 max 440 freq -37102 +/- 164 delay 2734 +/- 91 phc2sys[940.973]: rms 244 max 584 freq -37095 +/- 216 delay 2748 +/- 16 phc2sys[1000.979]: rms 220 max 573 freq -36666 +/- 182 delay 2747 +/- 43 phc2sys[1060.984]: rms 266 max 675 freq -36759 +/- 234 delay 2753 +/- 17