[time-nuts] Basic Stratum 1 question
Hal Murray
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
not-so-good tree.
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.
More information about the time-nuts
mailing list