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<== Date ==> <== Thread ==>

Subject: multiple NTP servers and NTPTime
From: "Kalantari Babak" <[email protected]>
To: "Andrew Johnson" <[email protected]>
Cc: [email protected], Korhonen Timo <[email protected]>
Date: Wed, 9 Dec 2009 09:54:56 +0100
Hi Andrew,

As you know, the current NTPTime provider of generalTime in EPICS polls
only to one NTP server which is specified by "EPICS_TS_NTP_INET". For us
(and probably others) it would be desired to enable the NTPtime provider
to be aware of multiple NTP servers such that if one fails to respond at
any point it could sync with a second (or third ...) NTP server. 

I see two ways of doing this and I wanted to know others' opinion which
one is better to go:

1. Having one generalTime-registered NTPTime provider (like now) but
making it to accept a list of NTP servers and it syncs to the first
available one. This can be done by making "EPICS_TS_NTP_INET" a list of
IP addresses and consequent modifications. 

2. Having multiple generalTime-registered NTPTime providers where each
of those can be configured with a simple (driver) configuration command
to set NTP server IP and one or two more parameters to distinguish
between NTPTime providers. In this case the NTPTime configurations have
to be called in a common startup.cmd at init time with one of them
having its NTP server as "EPICS_TS_NTP_INET". 

To me the first way looks simpler and involves fewer changes. Of course
I can always add a time provider to generalTime if I want to, but the
point here is that there is nothing different in such NTPTime providers
else than the NTP server address. For us such changes (either way) goes
to generalTime driver package as we use EPICS 3.14.8 but if desired it
can be introduced to the next EPICS version as the generalTime itself
and NTPTime provider are in base starting from 3.14.10.  
     
Any thoughts?

Regards,
Babak

===============
Babak Kalantari,  
Embedded Software Group,  
Paul Scherrer Institute, CH-5232 Villigen PSI
Tel:+41 56 310 5122  http://www.psi.ch/



Replies:
Re: multiple NTP servers and NTPTime Andrew Johnson

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