[ntp:questions] SNTP with 1ms of precision?

David J Taylor david-taylor at blueyonder.co.uk.invalid
Thu Jun 17 15:11:04 UTC 2010

> NTP can deliver a time accuracy of 1nsec?? I my point of view, NTP 
> includes
> methods to estimate the round-trip path delay between the server and 
> client
> but the performance is limited by SO stack latency, it is an Application
> Layer protocol.

Marcelo, here's what /my/ NTP achieves:


The top three PCs (Pixie, Feenix and Stamsund) are each fed with a serial 
GPS/PPS signal from a Garmin GPS-18 LVC or GPS-18X LVC.  Three different 
operating systems.

The bottom PCs are all Windows boxes of various versions, synced over a 
LAN including a cheapo Netgear GS608 1Gb/s switch, a WRT54GL Samknows 
performance measurement box, and a Netgear WNR2000v2 with wired and 
wireless connections.

I don't know whether any of those LAN-connected boxes would meet your 
"1ms" requirement (although if there were all running FreeBSD they would 
likely be significantly better than when running Windows).


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