[ntp:questions] Tiime Sync solution

Bjorn Gabrielsson bg at lysator.liu.se
Tue May 31 20:03:32 UTC 2005


John Pettitt <jpp at cloudview.com> writes:

> Adrian 'Dagurashibanipal' von Bidder wrote:
> > Clinging to sanity, Brad Knowles mumbled in his beard:
> 
> >>>relatively slow ADSL line, I'm usually down in the low single-digit 
> >>>*microsecond* region.
> > 
> > 
> > You sure?
> > 
> >     remote       refid     st t when poll reach   delay   offset jitter
> > ==========================================================================
> > +130.60.75.75 130.149.17.8  2 u   85 1024  377   20.503    1.772   0.429
> > *130.60.75.72 130.149.17.8  2 u   26 1024  377   23.294    2.103   0.415
> > +130.60.7.44  130.60.7.51   3 u  121 1024  377   19.054   -7.424   0.390
> >  192.168.1.17 192.168.1.254 4 u   84 1024  377    0.627   -2.502   0.860
> > 
> > (and offset=-1.94 in ntpq -c rv)
> > 
> > I was quite sure that these numbers are ms and not µs - are you really
> > down at 0.00x here?
> 
> I'm getting low 100's of microseconds locally and between 300-500
> microseconds accross a DSL link
> 
> jeeves# ntpq
> ntpq> pe
>     remote           refid    st t when poll reach delay offset jitter
> ==========================================================================
> *GPS_NMEA(0)     .GPS.          0 l   19   64  377  0.000  0.046 0.038
> -solar.localnet  192.168.2.254  2 u    2  256  377  0.678 -0.153 0.504
> +gatekeeper.no-s .GPS.          1 u  241  256  377  0.840  0.045 0.925
> +john-desk-2.loc 192.168.2.254  2 u   25  256  377  0.335  0.198 0.579
> -skipjack.no-suc 64.142.103.194 2 u    1  256  377 11.669  0.293 6.094
>  LOCAL(0)        73.78.73.84    5 l   27   64  377  0.000  0.000 0.002
> ntpq>
> 
> gatekeepr and solar are soekris 4801's - slow 586 class FreeBSD boxes.
>  john-desk-2 is a windows box on a gigabit land connection to jeeves
> (the server).   skipjack lives in a server farm but still manages to
> track the refclocks pretty well. This snapshot while a backup was
> running which is why the server is 48 us away from the refclock.
> 
> Now if I could only figure out why two identical 4801''s on the same
> switch have 160 us difference in round trip time ....

This is from a tiny adsl connection. 

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 LOCAL(0)        73.78.73.84      5 l   33   64  377    0.000    0.000   0.002
+                .PPS.            1 u  290 1024  377   11.568    0.111   0.280
-                .PPS.            1 u  246 1024  377   16.718    0.519   0.112
-                .PPS.            1 u  284 1024  377   21.166    0.253  38.112
+                .PPS.            1 u  237 1024  377   21.462    0.097   0.298
x                .PPS.            1 u  247 1024  377   20.407    1.662   0.140
+GPS_PALISADE(0) .GPS.            0 l   18   16  377    0.000   -0.001   0.002
*GPS_JUPITER(0)  .GPS.            0 l   23   64  377    0.000   -0.001   0.002

--
        Björn



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