[ntp:questions] broadcast client

rochertov at gmail.com rochertov at gmail.com
Sun Sep 28 19:13:39 UTC 2008

To provide some details about the setup and to clarify some points.
We are creating an emulated testbed for TDMA experiments, where
several machines connected over the same VLAN follow a TDMA schedule.
We have a second control network that is lightly loaded and does not
see any experimental traffic.  For us, it is critical to ensure that
all the nodes participating in the TDMA schedule have pretty much the
same time with a small offset (ideally under 100 micro-seconds).  For
the expriment, it is not important if the local time is anywhere close
to true global time, hence we don't synch with stratum 1 ntp server
(we have a flaky Internet connection).  Additionally, we are not
concenred with drift or clock skew that happens over periods of longer
than a few hours.  Ideally, we would have a GPS PPS pulse driving ntp
on the ntp server; however, we don't have one yet and have to use the
clock of the machine.  It was my impression of reading the documents
that frequent polling of a ntp server on the same fast LAN will
minimize time offsets, as that is our primary concern.  I also would
not call myself a non-beliver of ntp algorithms.  I am just trying to
configure ntp to best fit our needs, which are quite different from
the usual situation.

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