sub Millisecond is EASY. my Apple 27" iMac is doing that right now using just Internet pool servers. Yes I have a very good Internet connection. 100 Mbit fiber and then the last meter is 1000BaseT
But still, milliseconds are really EASY. It is sub microseconds that requires things like PTP and special hardware. It's at the uS level where you have to work hard If anyone needs to break a millisecond, just run the PPS to the machine that needs it edit /etc/ntp.conf and you are now in the "few uS" level. It costs nothing (if PPS is available.) But breaking that uS barrier is not easy On Thu, Feb 16, 2017 at 9:59 AM, shouldbe q931 <[email protected]> wrote: > On Thu, Feb 16, 2017 at 7:55 AM, Chris Albertson > <[email protected]> wrote: >> >> But PTP requires special hardware. You may not have this. >> > > I have to disagree. > > I run PTP on a Raspberry Pi using its onboard USB connected NIC, and > onboard NICs on HP and Dell servers, I see +- 5 microsoconds jitter in > the one way delay across 4 fanless HP switches, and when PTP is > running on a Pi with a GPS hat with PPS, I see +50 -30 microseconds > jitter in the reported offset from master across the slaves. > > If the requirement is for sub millisecond then PTP on commodity > hardware is a _workable_ solution. > > If sub microsecond accuracy is required, then the NIC, Ethernet switch > and time source hardware requirements change. > > Cheers > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
