Request for data / ntpsnmpd report
ianbruene at gmail.com
Tue Jan 9 18:52:16 UTC 2018
On 01/09/2018 11:42 AM, Eric S. Raymond wrote:
> Third way: there's a reference to get_resolution() ntp_systime.c at
> line 147 ("After default_get_precision() has set a nonzero sys_fuzz")
> that implies two things; (1) get_resolution() used to be called within
> ntpd, and (2) its role has been taken over by the system variable
> sys_fuzz, which is exposed through Mode 6. We could return that,
> scaling it as the RFC requires.
> I think the third way is probably best - returning sys_fuzz.
I'll look there.
>> * Time Distance
> This could refer to one of three concepts: "root distance", "root
> dispersion" "synchronization distance". I am not entirely sure these
> are all different things (!) as the documentation around them is
> remarkably obscure - I refactored the code without fully understanding it.
> I *think* "synchronization distance" is about the hop to the peer that
> shipped the most recent packet accepted, while "root distance" and
> "root dispersion" are the same statistic cumulated back to the root.
> Hal or Daniel might know more than I do here.
> If my belief is correct, you can fill this in with the mode 6
> "rootdisp" system variable. But I'd like a sanity check on this. If
> you're feeling brave, grep for these terms in the documentation and
> develop your own theory.
It isn't rootdisp, that is already covered by ntpEntStatusDispersion.
Will try to track the other(s).
>> * Validation for the TestSet sequence. According to the RFC this is one of
>> the most complicated parts of an agent to get right. Currently it is setup
>> to be failsafe, which we can get away with for now because the NTP MIB only
>> has two writable entries, and simple ones at that.
> I don't understand this at all. Where is it in the RFC?
Ah, I left that ambiguous. RFC 2741, which defines the AgentX standard.
Quick explanation: To write a variable the master first sends a TestSet
packet to queue and validate the changes. That is followed by one or
more of Commit/Undo/CleanupSet. The RFC defines several steps that the
TestSet handler needs to check in order to validate what it is trying to do.
(This question was directed at anyone with AgentX experience)
> I have no idea how to check for this either.
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