Hi, Miroslav: I am using calnex to test ptp. calnex can mimic the long path delay so it is reasonable. I am using switch chip, it has MAC timestamping and rx_delay, tx_delay are compensated.
Thanks Alex Miroslav Lichvar <mlich...@redhat.com> 于2022年9月8日周四 21:26写道： > On Thu, Sep 08, 2022 at 07:41:53PM +0800, Hamilton Alex wrote: > > ptp4l[130171.662]: rms 1 max 2 freq -49 +/- 3 delay 9058 > +/- 0 > > > my board has 1PPS output, I connect it to the master and compared with > > reference PPS. > > however, the 1pps time error is around 40 NS, which means my board is > > ahead of the reference for about 40NS, which doesn't match the result > > dumped by ptp4l. > > ptp4l is just printing the measured offset. It doesn't know the actual > error. > > A measured delay of 9 microseconds is huge. That's few kilometers of > cable. What hardware do you use? Does it have PHY or MAC timestamping, > and are those errors compensated? > > -- > Miroslav Lichvar > >
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