[ntp:questions] NTP tunning for OWD measurements
david at ex.djwhome.demon.invalid
Sat Oct 27 19:22:40 UTC 2012
pret3nder at gmail.com wrote:
> Yes, circuit switched networks don't have this problem,
> for sure.
> If, for example, having a GPS on S1, and using it as a
> timeserver for X1, and considering the incoming and outgoing
> delay on that path are equal, when measuring the OWD
> between S1 and X1, I would get a measurement with an accuracy
> equal to the offset reported by NTP, right?
Circuit switched networks are typically time-space-time switched, For
switches operating at the frame rate, that means each switching stage
can introduce a delay from 0 to almost 125 micro-seconds. Typically the
same time slot is used by both directions on a trunk, which I think
means that the round trip time gets 125 micro seconds per stage, but the
two directions will get different proportions of this.
(I may have used "stage" loosely.)
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