[ntp:questions] How is the NTP build tested?

Terje Mathisen terje.mathisen at tmsw.no
Tue Jan 14 10:28:06 UTC 2014


Harlan Stenn wrote:
> William Unruh writes:
>
>> And a standard has no business to specify how a program achieves the
>> goals.  It certainly has a business to specify what how the packets
>> are structured, and perhaps even suggest what standards it should
>> achieve in disciplining the clock, but how it does that should be no
>> business of the standard.  It would be like saying that all editors
>> should only use ASCII.
>
> I disagree with you.

You should probably state your reason(s) for doing so!

There is one big & sufficient reason for including the underlying 
algorithms in the standard, not just the packet format:

The entire NTP ensemble, from the current machine and up to all its 
sources, constitute a distributed control loop, right?

This means that the stability and eventual precision of any given clock 
depends upon exactly how all the source (server/peer) clocks behave, it 
is easy to come up with scenarios that will become unstable and lead to 
oscillating clocks.

This is of course not an issue for any leaf node (pure client), as they 
cannot propagate any introduced errors, but for server machines the 
hybrid FLL/PLL control loop is very much a part of the standard.

Terje
-- 
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"



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