[ntp:questions] SNTP Client/Server questions

Bryan Henderson bryanh at giraffe-data.com
Wed Aug 16 15:32:41 UTC 2006

>Basically, a valid SNTP server is supposed to be sourced directly from
>a reference, never from a remote NTP server.

Just to clarify: the recommendation is that the SNTP server get it
directly from a reference in preference to gettting it from a remote
server via SNTP (That remote server may or may not be an NTP server as
well).  But if the SNTP server gets it from a remote NTP server via
NTP, that's fine.

With both SNTP and NTP, it's always better to get time from a radio
clock rather than a remote server.  But if you set up a multilevel SNTP
tree, the leaves are going to be less accurate than in an NTP tree of the
same depth.  I.e. depth costs you more in SNTP than in NTP.

I think you have to take recommendations like this in the RFC with a
grain of salt, because the authors don't know what your requirements
are.  Maybe <500 ms accuracy isn't worth the price of either a radio
clock or NTP to you.  In that case, a 3-deep SNTP network could be the
best way to go.

Bryan Henderson                                    Phone 408-621-2000
San Jose, California

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