[ntp:questions] NTPd is not sync for some poll interval values
Gaurav Narain Mathur
narainmg at hotmail.com
Wed Feb 18 18:13:16 UTC 2009
> From: unruh-spam at physics.ubc.ca
> To: questions at lists.ntp.org
> Date: Fri, 6 Feb 2009 14:18:09 +0000
> Subject: Re: [ntp:questions] NTPd is not sync for some poll interval values
>
> narainmg at hotmail.com (Gaurav Narain Mathur) writes:
>
> >I have a problem where the NTPd would not sync the time with the
> >timeserver (10.0.0.1) if minpoll value is 7 and maxpoll is 8. It works
> >if the minpoll is 4 maxpoll is 5. Can anybody please help me out in
> >identifying what the problem could be? The "flash" never becomes
> >"0" I think. Also another host on the same subnet sync with the same
> >poll values and with the same server (10.0.0.1).
>
> Your offset its too large. Use ntpd -g to have it get rid of the large
> offset initially.
>
>
Thanks,. I'll try that. What puzzled me most was that a machine on the
same subnet, syncing with the same time server and with the same initial
time as the one I am working with syncs ok. The machine I am interested
in does not.
Digging in a little deeper, I have found that this might have something
to do with the routine precision values calculated on the two machines.
In the one where the minpoll and maxpoll of 7 and 8 work, the precision
is almost always calculated between 1-5 usec. The one I am working with
calculates the precision between 70-80 usec. I think this skews the
peer_unfit calculation to always be above the threshold value and the
peer is never deemed fit in my machine.
>
> >Any help is much appreciated. Debug output is attached below.
>
> >Thanks.
>
> >[...]
>
> >~ $ ntpq -c "pe"
> > remote refid st t when poll reach delay offset
> >jitter
> >=============================================================================
> >=
> > 10.0.0.1 64.247.17.254 3 u 117 128 377 1.125 -6423.0
> >1427.38
> >~ $ ntpq -c "pe"
> > remote refid st t when poll reach delay offset
> >jitter
> >=============================================================================
> >=
> > 10.0.0.1 64.247.17.254 3 u 14 128 377 1.160 -8010.8
> >1420.48
> >~ $
> >~ $
> >~ $
> >~ $ ntpq -c "as"
>
> >ind assID status conf reach auth condition last_event cnt
> >===========================================================
> > 1 63473 9014 yes yes none reject reachable 1
> >~ $
> >~ $
> >~ $ ntpq -c "rv"
> >assID=0 status=c011 sync_alarm, sync_unspec, 1 event, event_restart,
> >version="ntpd 4.2.4p4 at 1.1520-o Wed Feb 4 21:58:44 UTC 2009 (1)",
> >processor="mips", system="Linux/2.6.26.6", leap=11, stratum=16,
> >precision=-13, rootdelay=0.000, rootdispersion=27.375, peer=0,
> >refid=INIT, reftime=00000000.00000000 Thu, Feb 7 2036 6:28:16.000,
> >poll=6, clock=cd34a655.87cf0951 Wed, Feb 4 2009 23:42:13.530, state=0,
> >offset=0.000, frequency=0.000, jitter=0.122, noise=0.122,
> >stability=0.000, tai=0
> >~ $
> >~ $
> >~ $ ntpq -c "rv 63473"
> >assID=63473 status=9014 reach, conf, 1 event, event_reach,
> >srcadr=10.0.0.1, srcport=123, dstadr=10.0.0.9, dstport=123, leap=00,
> >stratum=3, precision=-20, rootdelay=93.857, rootdispersion=86.807,
> >refid=64.247.17.254, reach=377, unreach=0, hmode=3, pmode=4, hpoll=7,
> >ppoll=7, flash=400 peer_dist, keyid=0, ttl=0, offset=-8010.843,
> >delay=1.160, dispersion=1.989, jitter=1420.485,
> >reftime=cd34a51d.a5c4c862 Wed, Feb 4 2009 23:37:01.647,
> >org=cd34a636.e772df74 Wed, Feb 4 2009 23:41:42.904,
> >rec=cd34a63e.ea5f7fc8 Wed, Feb 4 2009 23:41:50.915,
> >xmt=cd34a63e.ea105e5d Wed, Feb 4 2009 23:41:50.914,
> >filtdelay= 1.16 6.87 5.52 1.29 1.03 1.12 5.75 1.10,
> >filtoffset= -8010.8 -7691.1 -7368.6 -7053.1 -6738.2 -6423.0 -6110.4 -5788.1,
> >filtdisp= 0.12 2.07 3.99 5.91 7.82 9.72 11.63 13.56
> >~ $
> >~ $
>
> >[...]
>
>
> >[...]
>
> >~ $ cat /etc/ntp.conf
>
> >###########################################################################
> >#
> ># Permit time synchronization with our time source, but do not
> ># permit the source to query or modify the service on this system.
> >restrict default kod nomodify notrap noquery
>
> ># Permit all access over the loopback interface. This could
> ># be tightened as well, but to do so would effect some of
> ># the administrative functions.
> >restrict 127.0.0.1
>
> ># Hosts on local network are less restricted.
> >#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
>
> ># Undisciplined Local Clock. This is a fake driver intended for backup
> ># and when no outside source of synchronized time is available.
> >fudge 127.127.1.0 stratum 10
>
> ># Drift file. Put this in a directory which the daemon can write to.
> ># No symbolic links allowed, either, since the daemon updates the file
> ># by creating a temporary in the same directory and then rename()'ing
> ># it to the file.
> >driftfile /tmp/etc/ntp/drift
>
> ># This command specifies the default directory path for cryptographic keys,
> ># parameters and certificates. The default is /usr/local/etc/.
> >keysdir /tmp/etc/ntp/
>
> ># Key file containing the keys and key identifiers used when operating
> ># with symmetric key cryptography.
> >keys /tmp/etc/ntp/keys
>
> ># Specify the key identifier to use with the ntpdc utility.
> >#requestkey 8
>
> ># Specify the key identifier to use with the ntpq utility.
> >#controlkey 8
>
> >###########################################################################
> ># Specify the key identifiers which are trusted.
> ># trustedkey 4 8 42
> >###########################################################################
> >#trustedkey
>
>
> >###########################################################################
> ># Add time servers here
> ># broadcast 192.168.1.255 key 42 # broadcast server
> ># broadcastclient # broadcast client
> ># broadcast 224.0.1.1 key 42 # multicast server
> ># multicastclient 224.0.1.1 # multicast client
> ># manycastserver 239.255.254.254 # manycast server
> ># manycastclient 239.255.254.254 key 42 # manycast client
> >###########################################################################
> >server 10.0.0.1 minpoll 7 maxpoll 8
>
> >[...]
> >_________________________________________________________________
> >Windows Live™: Keep your life in sync.
> >http://windowslive.com/howitworks?ocid=TXT_TAGLM_WL_t1_allup_howitworks_02200
> >9
>
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