Ntp Time Maximum Error
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NTP "maximum error" on local network Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] ajit.warrier at gmail.com wrote: > I
What Is Ntp Offset
am currently involved in a research project requiring tight time > synchronization ntp protocol port between nodes on an ethernet LAN. We require pairwise > time offsets between nodes to be accurate by ntp stratum levels less than 1ms. As a simple > test scenario, we set up a Linux machine with 2.6.16 kernel as our ntp > server and use the local clock as
Ntp Stratum 16
a reference: > > ------- /etc/ntp.conf at server ------------------- > restrict 127.0.0.1 nomodify > driftfile /var/lib/ntp/ntp.drift > server 127.127.1.1 prefer > fudge 127.127.1.1 stratum 0 refid NIST > > Two clients connect to this server through a 10Mbps hub, and get > synced. > > ------- on one of the client ------- > # ntptime > ntp_gettime() returns code
Ntp Polling Interval
0 (OK) > time c8164ed5.d3251000 Wed, May 17 2006 21:39:33.824, (.824784), > maximum error 41499 us, estimated error 2 us > ntp_adjtime() returns code 0 (OK) > modes 0x0 (), > offset -1.000 us, frequency 212.242 ppm, interval 4 s, > maximum error 41499 us, estimated error 2 us, > status 0x1 (PLL), > time constant 0, precision 1.000 us, tolerance 512 ppm, > pps frequency 0.000 ppm, stability 512.000 ppm, jitter 200.000 us, > intervals 0, jitter exceeded 0, stability exceeded 0, errors 0 > > > Clearly, I am able to achieve an "offset" of 1us and an "estimated > error" of 2us, which looks extremely good. But strangely, the "maximum > error" field gives an error of about 42ms. When I compare time stamps > between the server and client (at the MAC layer, to cancel out effects > of latency at higher layers), I see a gap of almost 60ms. Does anybody > have any idea of this kind of problem ? > > http://groups.google.com/group/comp.protocols.time.ntp/browse_thread/thread/3343cc5fec1b6597/effe74a33bb03cf2?q=accuracy&rnum=1#effe74a33bb03cf2 > > The above thread seems
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