[ntp:questions] Re: SNTP Client/Server questions
hmurray at suespammers.org
Wed Aug 16 18:56:28 UTC 2006
>thanks. We aren't looking for performance extremes... Would it be
>reasonable to get an accuracy within several seconds, feeding sntp
>clients on a lan from an sntp server which itself was fed from an NTP
>server on the net? Assuming a local clock which is nominally 60 ticks
>per second? And assuming the polls on both ends could be done often
>enough to account for local clock drifts?
That depends on how often you poll and how much your clock drifts.
"several seconds" is a long time relative to round-trip delays to
a nearby time server. Let's ignore those delays for now.
Several PCs I have access to are off by slighly more than 100 ppm.
There are 86K seconds per day. Call it 100K. So a crystal error of
10 ppm would turn into a clock error of one second per day.
So you would have to poll 10 times per day - once every 2 hours.
Back to network delays. Does your link to the outside world get
overloaded at times? That may confuse things.
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