[ntp:questions] PPS only configuration

Brian Utterback brian.utterback at oracle.com
Tue Jan 15 20:38:06 UTC 2013


You can't. The PPS feature can only use offsets up to .5 seconds. If the 
offset is greater than .5 the PPS will synchronize your system to the 
wrong second. In essence the PPS just locks the clock to the nearest 
second. So NTP PPS is designed to require another source of time and 
then on let the PPS kick in when the offset is below .5 seconds. If you 
circumvent that requirement, you run the rather high risk of being some 
integer multiple of seconds offset from the real time.


On 01/15/13 13:48, Edward T. Mischanko wrote:
> How do I configure NTPD so that only the PPS offset is used to figure 
> the clock offset, instead of factoring in the surviving back-up 
> servers that have bigger offsets?  I only want the back-up servers to 
> come into play when, or if, the PPS fails.
>
> #
> enable pps
> enable kernel
> enable ntp
> tos minclock 4
> tos minsane 3
> tinker huffpuff 7200
> #
> driftfile "/var/db/ntpd.drift"
> leapfile "/usr/home/ed/leap-seconds"
> #
> enable stats
> statistics loopstats
> statsdir "/usr/home/ed"
> filegen loopstats file loop type day
> #
> server 127.127.20.0 mode 18 minpoll 3 prefer
> fudge 127.127.20.0 time2 0.374000
> server 127.127.22.0 minpoll 3
> fudge 127.127.22.0 flag2 0 flag3 1
> server 192.168.1.254 iburst minpoll 6 maxpoll 6
> server tick.cerias.purdue.edu iburst minpoll 6 maxpoll 6
> server tock.cerias.purdue.edu iburst minpoll 6 maxpoll 6
> server tack.cerias.purdue.edu iburst minpoll 6 maxpoll 6
> server nist1-chi.ustiming.org iburst minpoll 6 maxpoll 6
> server nist.expertsmi.com iburst minpoll 6 maxpoll 6
> server nist.netservicesgroup.com iburst minpoll 6 maxpoll 6
> server ntp.your.org iburst minpoll 6 maxpoll 6
> server navobs1.wustl.edu iburst minpoll 6 maxpoll 6
> server utcnist2.colorado.edu iburst minpoll 6 maxpoll 6
> server time-a.timefreq.bldrdoc.gov iburst minpoll 6 maxpoll 6
> server ntp1.conectiv.com iburst minpoll 6 maxpoll 6
> server east-pool.ustiming.org iburst minpoll 6 maxpoll 6
> #
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-- 
blu

Always code as if the guy who ends up maintaining your code will be a
violent psychopath who knows where you live. - Martin Golding
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Brian Utterback - Solaris RPE, Oracle Corporation.
Ph:603-262-3916, Em:brian.utterback at oracle.com



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