[ntp:questions] Network problems affecting NTP

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Sat Jul 2 04:40:57 UTC 2011


In article <51c20190-11b8-4629-a762-cbf95369e68e at r18g2000vbs.googlegroups.com>,
 Eugen COCA <ecoca at eed.usv.ro> writes:
>Due to a network problem on our provider, the packets were routed on a
>different path than usual yesterday, for several hours. This period,
>NTP displayed wrong offsets:

ntpd assumes the network path is symmetric.  If it's not, the time
will appear to have an offset.

You can turn things around.  If you know the time at both sites,
you can measure the network delays.

If you turn on rawstats, ntpd will write a line to a log file for
each packet exchange.  (details in the html files)  You can graph
the offset and delays.  If you have a good connection, it's easy
to spot network topology changes.


-- 
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