[ntp:questions] NTP for dummies

Brian T. Brunner brian.t.brunner at gai-tronics.com
Fri Sep 30 14:55:10 UTC 2005


There can be, and should be, an "NTP For Dummies", because us dummies
want NTP to do something it was NOT designed to do.

NTP was designed to make possible that an amorphous wide-area fuzzy set of machines can ALL stay synchronized to UTC.

What you want is something to keep a local-area network of machines to agree with each other on the local time.
The pounding you hear when you're NOT pounding YOUR head is me pounding mine.

So: How to configure this high-mobility armored combat troop transport to do the lawn-tractor job you have in mind:
MASTER must declare itself to have a stratum above 16.  10 is a common choice for this.  It also must be synchronized to it's local clock.
SLAVES must look to MASTER as their server.
Ergo MASTER must have rules that allow the SLAVE machines to request and get time.  
How complex these rules are depends on things not yet known to me/us:  
Are you in a closed environment, meaning no possible hostile users/machines?
Is there a "secondary master" to listen to when/if the MASTER isn't online?

My target was closer to yours than to NTP's design function.  
I don't care what UTC stands for, much less what value it has.  Yes, I'm a blasphemer and a pervert.  It's my job.
I have possibly one server, a senior client, and 0-11 other clients.
All systems in the site are to report any particular event (alarm/page/party comms product) as happening at the same time-of-day.
Important: an alarm starting on one system shall NOT be reported as being acknowledged as received on another system in the site before, nor more than a few seconds after, the time it occurred on the originating system. 
A wise customer will get UTC into the (optional) server, but that's his responsibility.
The Server (SCADA or mytrustedtimeserverip) is a WinNT or WinXP system; 
my responsibility is the senior client "mcut16" (which may be stand-alone) and the 0-11 other clients.
Here are the ntp.conf files for the senior client, and for the 0-11 other guys.
I'm on a "safe" network, security from hostiles is not a concern.

restrict default ignore
restrict 127.0.0.1
restrict 192.168.1.0 mask 255.255.255.0
server  mytrustedtimeserverip prefer iburst	# scada
server  127.127.1.0
fudge   127.127.1.0 stratum 8
driftfile /etc/ntp/drift

restrict default ignore
restrict 127.0.0.1
restrict 192.168.1.0 mask 255.255.255.0
server  mytrustedtimeserverip prefer iburst
server  mcut16
server  127.127.1.0
fudge   127.127.1.0 stratum 10
driftfile /etc/ntp/drift

Turning this information into an NTP For Dummies probably exceeds my grasp of this rather powerful and complex tool.

Brian Brunner
brian.t.brunner at gai-tronics.com
(610)796-5838

>>> Cam <camfarnell at cogeco.ca> 09/30/05 01:01AM >>>
Hello list,

I've been alternately reading the NTP documentation and banging my head 
on the desk, so please excuse any intemperance and/or incoherence.

look for the NHBP (Network head-banging protocol); we should bang in synchrony.

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