On 2 September 2011 07:56, unruh <un...@wormhole.physics.ubc.ca> wrote:
> > Nope. > > It is completely unclear to me what your question is. Your 10.0.2.254 is > an outside switch. I had several questions in my first message. Your assumption is wrong. You are telling me that a switch I installed in my rack and defined its many IP addresses is outside my company? Uau! 10.0.2.254 is a local as any machine in the 10.0.0.0/8 network. >> > $ ntpq -p 10.0.99.99 > >> > remote refid st t when poll reach delay offset > >> > jitter > >> > >> > >============================================================================== > >> > *10.0.2.10 .GPS. 1 u 21 256 377 0.173 0.196 > >> > 0.008 > >> > +10.0.2.9 .GPS. 1 u 93 256 377 0.175 0.191 > >> > 0.014 > >> > +10.0.2.254 81.94.123.16 2 u 149 256 377 0.583 -6.884 > >> > 0.152 > > This tells me that your two GPS receivers are consistant with each > other, but I have no idea why the offset is larger than the delay, and > why the offsets are so large. On a lan, the offsets should be a factor > of 20 or so less than what you are getting here. > That the external router is 7 ms out just tells me that it is really > poorly synced with the outside world. > I found out the problem and just for the record I'll explain... The offset is larger than the delay because NTPd is using 10.0.2.254 (more on this switch later) as a time source and it shouldn't because it has two local stratum 1 clocks that are closer (0.170 ms vs 0.583 ms) are show less jitter. Anyway... to prove my point I removed 10.0.2.254 (the **internal** switch) from the configuration and here's the result of ntpq -p as of now: $ ntpq -p 10.0.2.2 remote refid st t when poll reach delay offset jitter ============================================================================== +10.0.2.10 .GPS. 1 u 889 1024 377 0.179 -0.066 0.083 *10.0.2.9 .GPS. 1 u 391 1024 377 0.166 -0.084 0.051 Oddly enough, FreeBSD embedded machine with roughly the same NTP configuration shows better results $ ntpq -p 10.0.99.99 remote refid st t when poll reach delay offset jitter ============================================================================== +10.0.2.10 .GPS. 1 u 864 1024 377 0.193 0.025 0.301 *10.0.2.9 .GPS. 1 u 1012 1024 377 0.192 0.030 0.004 Regarding 10.0.2.254 it is an internal switch it is getting time over a cable connection from several sources $ ntpq -p 10.0.2.254 remote refid st t when poll reach delay offset jitter ============================================================================== -ntp0.as34288.ne .PPS. 1 u 391 1024 377 71.960 -1.029 0.270 *canon.inria.fr .GPSi. 1 u 707 1024 377 55.220 0.199 0.700 +ntp1.inrim.it .CTD. 1 u 359 1024 377 65.860 0.091 1.830 +ntp-p1.obspm.fr .TS-3. 1 u 373 1024 377 55.110 -0.215 0.610 -metasweb01.admi .HBGi. 1 u 992 1024 377 73.290 -5.182 0.850 I can't control the network at my upstream provider and while my link is not saturated (far from that) my upstream provider links be could and there's nothing I can do about it except deploying local time sources as I did. I am checking my local time sources with some remote NTP stratum 1 servers at a fixed interval and plotting the results. I see that once in a while the offset to external time servers increases and I agree this has to be with network congestion but this happens at my ISP so there's not much I can do. >> > This is a FreeBSD embedded PBX machine running Asterisk. The machine is > >> > mostly idle. What kind of offsets should I get with local machines? > >> > >> in the 10s of usec range max. Certainly less than the delay. > >> > > > > tens of usec is good... Anyone here which can explain why NTP isn't > getting > > that? > > How could we? > Maybe you are running a virtual BSD machine, and thus the clocks are > wonkey. Maybe you have lousy hardware. Who knows. > No lousy hardware here but I think posting detailed hardware specifications won't help. No virtualization here also. >> > Assuming ntp04, ntp05 and ntp06 are on the same LAN I see offsets > higher > >> > than 100 us. Is it possible to decrease these numbers? > >> > >> Sure. all my systems have offsets in the 10us range-- on the same lan > >> as my time server. > >> Mind you I do use chrony, not ntpd but even ntpd should be in a few 10s > >> of usec. > > > > > > Can ntpd really get there? I'll try to query some good public servers to > see > > what others are getting... > > Sure it can. It can get better than 30us. But why you are not getting it > is impossible for us to say. I got it... As you saw above. _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions