[time-nuts] Basic Stratum 1 question
hmurray at megapathdsl.net
Thu Aug 2 13:40:33 EDT 2007
> Stratum 1, in the ntp world, is a source that's connected to an
> official source of time (the so-called Stratum 0). The CMOS clock
> isn't connected to NIST, therefore it can't be considered Stratum 1 by
> any stretch of the imagination.
> Also, Stratum 1, in telco, has certain performance requirements.
It's worth pointing out that "stratum 1" in the ntp world doesn't say
anything about quality.
The ntp stratum levels form a tree. Within a tree, lower stratum is better.
Given two trees, the root of one may be much better than the other. The
stratum-3 branches on the good tree may be more accurate than the root of the
ntpd supports a wide collection of clocks. Some are accurate to a few
microseconds, some are only good to tens of milliseconds. The protocol
includes an estimate of the quality so the client can pick the best clock.
These are my opinions, not necessarily my employer's. I hate spam.
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