[ntp:questions] NTP constant delay ?

unruh unruh at invalid.ca
Thu Dec 27 22:21:03 UTC 2012

On 2012-12-27, Ran Shalit <ranshalit at gmail.com> wrote:
> On Thu, Dec 27, 2012 at 11:24 AM, unruh <unruh at invalid.ca> wrote:
>> delay be constant within 100msec, meaning
> Hi,
> SNPT performance with talks about accuracy of 100msec are shown in the
> following white paper:
> http://www.cisco.com/en/US/tech/tk869/tk769/technologies_white_paper09186a0080117070.shtml

Try it. See what you get. 
Or put in ntpd or chrony and get a few microsecond accuracy.

> In out configuration we are talking about 2 machines, one using Linux
> SNTP client, the other I do not know, but assume it is RT Operating
> system. both machines are connected through ethernet.

Whatever RT operating system is. 

> It seems that if we use SNTP (as is required right now), we can't
> assure more accuracy then 100msec (according to that document), which

And you believe all documents you read on the web?

> might be probematic with our video sync requirements which are talking
> about less then 40msec.
> I appreciate any comments or ides,

SNTP is not a program. It is a protocol, used for a) delivering time
from a stratum 0 time source, or b) receiving time on a machine which
will not server it to anyone else. ntpd is the stadard ntp program.
chrony is in many cases more accurate. Both will give 10s of
microseconds (not milliseconds) on Linux/bsd.. systems. Only ntpd works
on windows. 

> Regards,
> Ran

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