I am currently looking to do something similar. My requirements are longer term, and much more accurate (we're aiming for 5ms across a large number of servers).
I did some poking around, and I found this perl script and have been fiddling with it. I wish I was more of a time nerd (no offense meant) and could understand all the output, but I think what you (and I) want is here somewhere: http://www.kloth.net/software/sntp.php In particular, it calculates how far off the polled server is from the source you're querying from. If you were/I were to query from my master ntp clock to all servers, on a frequent basis, we'd be able to see changes and report on them fairly easily. I am trying to find something a little more robust and enterprise quality, but this will do until I can do that. Someone out there must have written something enterprise class to monitor time across a network, I just need to find them! Cheers, Todd. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Hushpuppy Sent: Tuesday, December 09, 2008 11:30 AM To: [email protected] Subject: [ntp:questions] Need to verify the offset Hi, I have a machine that is syncing to a Stratum-2 server which is syncing to a Stratum-1 server, which has a GPS Stratum-0 device attached to it. At my work (financial services) the market rules mandate synchronizing our clocks to within a maximum 3 second difference of the NIST atomic clock. We also need to log/document that we are within 3 seconds. So I have been perusing the output of ntpq but I don't fully understand it after some time of study. I assume I could use the pe command to figure out what my current offset is, and then as to determine my assID, and finally rv <assID> to look at my peers. Then I could perhaps add the current offset of my current peer, to one of the numbers from the rv command (rootdispersion?), to arrive at a maximum offset from my Stratum-1 server, and thus from NIST time (+- 100 microseconds or whatever the guarantee is for the Stratum-0 device). When I say "guarantee" I really think we're talking about best effort. BTW, RFC1305 says that rootdispersion is in seconds but I think it's really in milliseconds. Can anyone help? Given the below results from ntpq, what numbers would I need in order to determine my maximum deviation from NIST time at this current point in time? Can I even determine that from my client machine here, or do I need to login to all servers: Client, plus Stratum-2, plus Stratum-1, to arrive at a legitimate value? Thanks. ntpq> pe remote refid st t when poll reach delay offset jitter ======================================================================== ====== *XX.XX.XX.21 XX.XX.XX..1 2 u 236 1024 377 0.390 -0.060 0.017 +XX.XX.XX..22 XX.XX.XX.1 2 u 980 1024 377 0.333 1.797 0.081 127.127.1.0 .LOCL. 10 l 39 64 377 0.000 0.000 0.001 ntpq> as ind assID status conf reach auth condition last_event cnt =========================================================== 1 11015 9614 yes yes none sys.peer reachable 1 2 11016 9414 yes yes none candidat reachable 1 3 11017 9014 yes yes none reject reachable 1 ntpq> rv 11015 assID=11015 status=9614 reach, conf, sel_sys.peer, 1 event, event_reach, srcadr=XX.XX.XX.21, srcport=123, dstadr=YY.YY.YY.16, dstport=123, leap=00, stratum=2, precision=-18, rootdelay=106.873, rootdispersion=7.431, refid=10.30.25.1, reach=377, unreach=0, hmode=3, pmode=4, hpoll=10, ppoll=10, flash=00 ok, keyid=0, ttl=0, offset=-0.060, delay=0.390, dispersion=18.684, jitter=0.017, reftime=cce8d703.3ffd812a Tue, Dec 9 2008 5:37:39.249, org=cce8fc6c.762843fb Tue, Dec 9 2008 8:17:16.461, rec=cce8fc6c.763b45df Tue, Dec 9 2008 8:17:16.461, xmt=cce8fc6c.761d72f9 Tue, Dec 9 2008 8:17:16.461, filtdelay= 0.43 0.39 0.50 0.36 0.41 0.46 0.42 0.45, filtoffset= -0.08 -0.06 -0.10 -0.23 -0.31 -0.41 -0.46 -0.58, filtdisp= 0.00 15.38 30.77 46.13 61.50 76.85 92.21 107.60 _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions --------------------------------------------------------------------- This transmission (including any attachments) may contain confidential information, privileged material (including material protected by the solicitor-client or other applicable privileges), or constitute non-public information. Any use of this information by anyone other than the intended recipient is prohibited. If you have received this transmission in error, please immediately reply to the sender and delete this information from your system. Use, dissemination, distribution, or reproduction of this transmission by unintended recipients is not authorized and may be unlawful. _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
