On 3/17/2012 11:48 AM, David J Taylor wrote:
You'd get less jitter with DSL.
--
John Hasler
John,
You have piqued my interest. I have just set up a Windows-8 PC with
an ntp configuration not dissimilar to Ron's, in that it's using
purely Internet servers but trying to monitor a local stratum-1 server
as well. In essence:
______________________________
# Local stratum-1 Free BSD server
server 192.168.0.3 iburst minpoll 5 maxpoll 5 prefer noselect
# Seven external servers:
server x.x.x.uk iburst
server y.y.y.uk iburst
server 0.uk.pool.ntp.org iburst
server 1.uk.pool.ntp.org iburst
server 2.uk.pool.ntp.org iburst
server 0.nl.pool.ntp.org iburst
server 1.nl.pool.ntp.org iburst
______________________________
The performance will appear here:
http://www.satsignal.eu/mrtg/performance_torvik.php
It will be interesting to see whether the Internet servers poll period
increased from 64s (I'm hoping that the 32s poll on the local server
won't affect the Internet ones), and what level of jitter is achieved.
Cheers,
David
Hi David,
I'm not sure what will happen if you simultaneously prefer and noselect
the local server. Assuming the local stratum 1 server is the most
stable time source, you'll get a much better picture of what the
internet servers are doing relative to it if you allow it to be
selectable as well as being preferred. When you graph it, if the local
server is the active clock, all the lines for the internet servers will
be gathered around and relative to the local server. When I tried to do
things the other way around, with an internet server preferred, the
graph looked awful because there was so much variation. Also, if your
local server starts reporting time that looks too far from the internet
servers, regardless of who's fault it is, ntp will clock hop over to the
internet servers.
I don't THINK your internet servers will ever poll above their default
minpoll value of 6, or 64 seconds.
I realize you don't have a gps attached to this pc, but the iburst lines
reminded me of something. I read somewhere that having iburst on
internet server lines, if a local gps is attached, could prevent the PC
from synchronizing to the gps before it synchronizes to the internet.
On my pc with the gps attached, I don't use the iburst command.
Sincerely,
Ron
--
(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such. I don't always see new messages very quickly. If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)
Ron Frazier
timekeepingdude AT c3energy.com
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