Re: [chrony-users] Dealing with SNTP sources

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On Wed, 4 May 2011, Harald Krammer wrote:

Am 2011-05-04 20:04, schrieb Bill Unruh:
On Wed, 4 May 2011, Harald Krammer wrote:

I have a question about dealing with SNTP sources.

when I interact with two SNTP servers (also named as NTP server),

An sntp server must, AFAIK be a stratum 0 server.

Really? My opinion is, that the stratum behavior is equal. SNTP means  a
usage of simple algorithm. e.g. only hard time set after a query
Some  SNTP implementation are extremely inaccurate.  In my area NTP is
also used over GPRS connections ( round trip delay till 100 ms - 2 s).
Accuracy does not play a major role in some applications.

That may be your opinion, but sntp has a specific definition within the
standards and as far as I understand it, it is either a client only, or it is
stratum 0 server. It is not ever something which takes time from one server
and serves it to some other client.

In fact, the staunch proponents (David Mills) would even regard chrony as an
sntp and not allow a machine running chrony to serve time to anyone else. (Of course what you do in the confines of your own little private net is up to

Mills feels that he carefully designed ntp to give stable, reliable time to
others, and the simplifications stuck into sntp can easily destroy that ( as
you have done by relabeling stratum) reliability/stability, and that allowing
sntp into the time network would just bring it crashing down into chaos.
 I have some sympathy for his position.

William G. Unruh   |  Canadian Institute for|     Tel: +1(604)822-3273
Physics&Astronomy  |     Advanced Research  |     Fax: +1(604)822-5324
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