[ntp:questions] Re: Server sync changed from 3ms to 75ms

holmezy at yahoo.com holmezy at yahoo.com
Fri Jan 7 17:32:11 UTC 2005


Dave,

Thanks for the response!  Yes, we are aware of the demise of TrueTime.
However, you might like to know we purchased 2 TS2100s in the past
year.  One configured to receive IRIG-B, the other GPS.

As for our configuration, this lab architecture was inherited and out
of our control.  We are working toward making our fielded configuration
more robust and able to take advantage of NTP's built-in redundancies.

The differences are being  measured between our Regatta servers using
the timedc and ntpq commands.  Each Regatta is on its own LAN and
communicates to the other Regatta's via an emulated WAN using SHUNRA's
to impose real-world long haul comm constraints (packet loss, delay,
jitter, etc).

Currently, the lab where these machines are located is in configuration
lock-down.  We'll be able to investigate the jitter between the servers
sometime next week.

Based on this information, when the software we're testing performs the
timedc command between the servers, the differences are actually
between the Regatta system clocks, which are supposed to be in sync
from their NTP requests to the NTS100i units.  It's strange because
sometimes we're 1-3ms and then it will suddenly grow to +/-75ms.  It's
also inconsistent when you are sitting on each machine and checking the
clock differences.  We're also discussing reducing our polling time if
we conclude that the machines are experiencing too much drift between
the polling intervals.
Once again, thanks for the response,

John Holmes




More information about the questions mailing list