[154287] in North American Network Operators' Group
RE: [c-nsp] NTP Servers
daemon@ATHENA.MIT.EDU (Keith Medcalf)
Sat Jun 30 18:40:11 2012
Date: Sat, 30 Jun 2012 16:39:36 -0600
In-Reply-To: <8C6A44F7-FBC7-4F42-9830-22572A96FF3C@puck.nether.net>
From: "Keith Medcalf" <kmedcalf@dessus.com>
To: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
> Or you can ask the it guys to use a windows server... Eg:
>
> http://support.microsoft.com/kb/816042
That is a joke Jared? You left off the smiley.
Windows doesn't do NTP out-of-the-box (Microsoft assertions to the contrary=
notwithstanding). You can build a reasonably working standard daemon, how=
ever don't expect time to be very accurate. Windows out-of-the-box can kee=
p time +/- 10 minutes or so using the Microsoft lets-pretend-NTP.
You can build the current standard NTPD distribution on Windows. You can a=
lso spend lots of time to make it "work as well as possible" (once you mana=
ge to get it to compile, that is). Even so, when you have configured it to=
the optimality of accuracy, this is what you can expect:
remote refid st t when poll reach delay offset jit=
ter
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D
+tic.nrc.ca .PPS. 1 u 13 64 377 55.544 5.913 0.=
870
-tac.nrc.ca .ATOM. 1 u 48 64 377 56.188 4.768 3.=
041
-toc.nrc.ca .ATOM. 1 u 1 64 377 55.485 4.758 0.=
981
+tick.usask.ca .GPS. 1 u 34 64 377 19.566 6.942 5.=
699
*tock.usask.ca .GPS. 1 u 29 64 377 19.665 5.955 1.=
937
-clock.isc.org .GPS. 1 u 37 64 377 53.091 8.311 0.=
649
+clock.sjc.he.ne .CDMA. 1 u 48 64 377 43.591 6.066 2.=
501
offset: 0.005955 s
frequency: 23.346 ppm
poll adjust: -30
watchdog timer: 47 s
is about the best you will get. Statistics are pretty awful:
Date # O.Avg O.Median O.Range O.CI O.Skew O.Kurt =
F.Avg F.Median F.Range F.CI F.Kurt
2012-01 899 0.765559 0.004198 20.05221 0.000371 -0.56023 0.75115=
1 21.31698 20.9705 2.9685 0.108050 -0.88068
2012-02 9673 0.237434 -7.46502 59.75607 0.000156 -1.43583 8.60908=
5 19.01126 19.3495 5.2995 0.040683 -0.54578
2012-03 1380 -0.02157 -14.8416 44.00043 0.000124 -1.08589 4.55904=
9 18.08941 16.822 7.536 0.045387 0.268831
2012-04 1322 0.196654 21.16261 106.1250 0.000141 -0.48643 26.0586=
8 17.56811 16.812 6.111 0.040561 -0.38021
2012-05 8849 0.118125 27.44213 72.01526 0.000161 0.296114 8.93942=
9 17.88685 15.2595 9.3195 0.080186 1.121740
2012-06 1457 0.409662 -20.2809 63.32684 0.000114 -1.44144 11.9823=
7 20.50724 19.5425 6.7425 0.042372 -0.08891
6102 0.201651 21.16261 106.1250 6.065429 -0.84354 13.7816=
1 18.71838 16.1125 10.1725 0.023443 1.215941
This is from a custom ntpd build using the highest precision that it can ma=
nage to coerce from Windoze.
Of course, this may be accurate enough for most uses -- at least it does no=
t have to time-step.
Doesn't compare to ntpd on linux on an 80286 with 640K ram booting from a f=
loppy, which can maintain time sync within less than 1 ms easily.
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