On Fri, 14 Oct 2022 at 23:32, Gert Doering via cisco-nsp <cisco-nsp@puck.nether.net> wrote:
> For a true time geek, the time the rPIs provide is just not good > enough (fluctuates +/- 20 usec if the rPI has work to do and gets > warm) :-) Meinberg does not do HW timestamping, nor does NTP. Almost every NIC out there actually does support HW timestamping, but you'd need chrony to actually enable the support. When using Meinberg and clocking your host, ~all of the inaccuracy is due to SW timestamping, oscillator doesn't matter. Basically with NTP you are measuring the host context switch times in your jitter. This is because networks have become organically extremely low jitter (because storing packets is expensive). We see across our network single digit microsecond jitters (in my M1 computer I see loopback pings having >50us stddev in latency), and because the timing we use is SW timestamp, our one-way delay measurement precision is measuring the NTP host kernel/software context switch delays. The most expensive oscillator would do nothing for us, but HW timestamping and cheap 2eur OXCO would radically improve the quality of our one-way delay measurements. -- ++ytti _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/