On Fri, Jun 12, 2015 at 05:18:57PM -0500, Robb wrote: > I have two freshly installed machines that I am trying to sync the > CLOCK_REALTIME between the two. Do I need to have them get close in > time using ntp before I can use PTP?
No. > How far apart can the clocks be and still have PTP work? You can correct any offset by letting ptp4l reset the clock (which is the default setting). > They currently have a difference of 36 seconds but ptp4l and phc2sys > are both telling me <5uS. The 36 second offset [1] is the result of a configuration error. Your system time is UTC but PTP uses the TAI time scale. See the section titled "TIME SCALE USAGE" in the phc2sys man page. > Machine1 (master): > sudo ptp4l -i eth1 -m -2 -q > sudo phc2sys -s CLOCK_REALTIME -c eth1 -O 0 -u 60 > > Machine2: > sudo ptp4l -i eth0 -m -2 -q -s > sudo phc2sys -s eth0 -c CLOCK_REALTIME -w -u 60 If your network is not connected to the outside world WRT time, then the TAI offset is not so important. Just leave off the the "-O 0" on the master node, since that is wrong in any case. Thanks, Richard 1. Actually I would expect 35 and not 36. ------------------------------------------------------------------------------ _______________________________________________ Linuxptp-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linuxptp-users
