[ntp:questions] frequency adjusting only

Unruh unruh-spam at physics.ubc.ca
Wed Apr 23 17:28:08 UTC 2008


m.louvel at gmail.com (maxime louvel) writes:

>Hi,

>- my network contains only one switch, and all the node are in the same
>room.
>Thus I don't think cabling is a problem. I still have to check the latency
>of the switch.

>- I can't use a GPS or other material. I though I wouldn't need any because
>I don't won't a great accuracy with the real time, just between my nodes. I
>also think it would have been easier and better to have a common high
>precision time source (GPS)... But I can't afford that ;)

A garmin 18LVM is about $60. That is all you need plus a bit of soldering
so as to  put on the approriate plugs. 


>Do you have an explanation of the so different performances observed in your
>NTP synchronisations ?

Nope. All I can tell you is what I see. Maybe we have better switches here.



>- I'm going to look at chrony, which at first glance seems usable in my
>case.

>- I am already using the -x option, to be certain to avoid any step.

>Maxime

>On Wed, Apr 23, 2008 at 2:10 AM, Unruh <unruh-spam at physics.ubc.ca> wrote:

>> Steve Kostecke <kostecke at ntp.org> writes:
>>
>> >On 2008-04-22, Unruh <unruh-spam at physics.ubc.ca> wrote:
>>
>> >> Steve Kostecke <kostecke at ntp.org> writes:
>> >>
>> >> ??? In my experience, on a Lan ntpd shows an internode offset of about
>> >> 5-15 usec, and on the internet (ADSL) an offset of about 200usec.
>>
>> >Here's an aggregated plot of the node offsets on my LAN over the last 24
>> >hours. I see +3/-5 milliseconds, not anything near 5-15 microseconds.
>>
>> >
>> http://support.ntp.org/bin/viewfile/Users/SteveKostecke?rev=1;filename=typical_aggregate_lan_offsets.png
>>
>> I agree those are pretty bad. HOw are they hooked up? It looks like one of
>> the hops is via a telephone modem!
>>
>> See www.theory.physics/chrony/chrony.html
>> Mind you those are running with maxpoll 7 not maxpoll 10 (Its my lan and
>> ntp server, and I'll do what I want to.)
>>
>>
>> >--
>> >Steve Kostecke <kostecke at ntp.org>
>> >NTP Public Services Project - http://support.ntp.org/
>>
>> _______________________________________________
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>> https://lists.ntp.org/mailman/listinfo/questions
>>



>-- 
>Maxime Louvel
>0044 7964 5555 80
>43 Allen road
>Whitemore reans
>WV60AW Wolverhampton
>United Kingdom




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