Date: Mon, 08 Feb 2010 16:38:46 -0800 From: Chuck Swiger <cswiger@mac.com> To: DAve <dave.list@pixelhammer.com> Cc: 'User Questions' <freebsd-questions@freebsd.org> Subject: Re: NTP Stratum Message-ID: <964ACE53-30E5-4CF0-AE3E-200EFA368CFC@mac.com> In-Reply-To: <4B701CC8.6010407@pixelhammer.com> References: <4B6C94C7.6030609@pixelhammer.com> <4B6CBCA1.4080108@radel.com> <4B701CC8.6010407@pixelhammer.com>
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On Feb 8, 2010, at 6:16 AM, DAve wrote: > I am syncing with three server from N.us.pool.ntp.org. I have no fudge > configured. > > ]# ntpq -c peers > remote refid st t when poll reach delay offset > jitter > ============================================================================== > ns-01.tls.net .INIT. 16 u - 1024 0 0.000 0.000 > 4000.00 > +www.broadbandja 66.250.45.2 3 u 510 1024 377 61.944 3.528 > 0.230 > *point2.adamants 128.138.140.44 2 u 447 1024 377 59.360 0.863 > 0.154 > +66.36.239.104 69.64.37.141 3 u 507 1024 377 28.763 2.623 > 1.182 > > I am pretty sure I am just reading the man pages incorrectly, but then > others things seem confusing as well. A stratum-0 timesource is a reference clock like a GPS signal, atomic clock, or other very-high-quality timesource. A computer running ntpd can sync time to such a device, and will thus be a stratum-1 timeserver. Seeing NTP packets claiming to be stratum-0 is a sure indication that the ntpd thinks it is not properly synchronized, and NTP clients should ignore this timesource as a consequence. See: http://www.ntp.org/ntpfaq/NTP-s-algo.htm#Q-ALGO-BASIC-STRATUM "The stratum is a measure for synchronization distance. Opposed to jitter or delay the stratum is a more static measure. Basically (and from the perspective from a client) it is the number of servers to a reference clock. So a reference clock itself appears at stratum 0, while the closest servers are at stratum 1. On the network there is no valid NTP message with stratum 0." [ ... ] > I vote for higher, I have no fudge configured and my servers are > claiming to be stratum 0 when I check them from outside. But!! Never > trusting my observations until checking again, I see when I tested that > my clocks were off. So if I cannot sync, my server continues to answer > time queries but claims to be stratum 0. > > I am thinking I am getting closer to grasping this. That's correct. If you run something like: # ntpq -pc rv localhost assID=0 status=06f4 leap_none, sync_ntp, 15 events, event_peer/strat_chg, version="ntpd 4.2.4p5-a Tue Jan 12 18:52:12 EST 2010 (1)", processor="i386", system="FreeBSD/6.4-STABLE", leap=00, stratum=2, precision=-19, rootdelay=33.115, rootdispersion=28.426, peer=51948, refid=18.26.4.105, reftime=cf1b25fa.21d555c1 Mon, Feb 8 2010 19:08:26.132, poll=9, clock=cf1b2a9f.c570e0a6 Mon, Feb 8 2010 19:28:15.771, state=4, offset=-0.042, frequency=19.313, jitter=1.902, noise=0.625, stability=0.001, tai=0 remote refid st t when poll reach delay offset jitter ============================================================================== +ntp.pbx.org 192.5.41.40 2 u 477 512 377 30.744 1.763 0.702 *bonehed.lcs.mit .GPS. 1 u 165 512 377 33.115 -0.495 0.157 -hickory.cc.colu 128.59.39.48 2 u 482 512 377 30.943 3.618 0.468 +time1.apple.com 17.72.133.55 2 u 465 512 377 54.572 1.374 8.022 rrcs-24-103-228 18.26.4.105 2 u 505 512 377 34.623 -11.983 1.139 rrcs-24-103-228 .INIT. 16 u - 512 0 0.000 0.000 0.000 ...pay attention to the status in the first line, which in the above case reads "sync_ntp". I bet you're getting sync_unspec for your status. Regards, -- -Chuck
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