Re: Trace ntp sanity checks?

Hi,

thank you very much for your responses.

summary:
you see no reason, why a ntp-client that does not serve its time to
someone else should have a local clock configured?
did i get this right?

i will change my configuration and try that.

does anyone of you have details regarding my original question:
How can i find out which of the sanity-checks failed?



regards
Frank




-----Original Message-----
From: DE/SYS Routing - Linux, Team

Sent: Friday, December 07, 2007 9:16 AM
To: D1/OBT-ho Hornung, Frank; D1/OBT-ha Harle, Christoph
Subject: FW: Trace ntp sanity checks?


-------------------------------------------
From: questions-bounces+linux=stihl.de@lists.ntp.org on behalf of
[email]david@ex.djwhome.demon.co.uk.invlid[SMTP:DAVID@EX.DJWHOME.DEMON.CO.UK.IN[/email]
VLID]
Sent: Friday, December 07, 2007 8:56:31 AM
To: [email]questions@lists.ntp.org[/email]
Subject: Re: Trace ntp sanity checks?
Auto forwarded by a Rule

In article <4758C2A7.9080307@comcast.net>,
Richard B. Gilbert <rgilbert88@comcast.net> wrote:
[color=blue]
> The local clock driver[/color]
[color=blue]
> is harmless as long as people configure it to stratum 10![/color]

This very thread demonstrates a case where it wasn't harmless!

What has happened here appears to be that it has provided a much more

attractive indication of the time than proper time sources. I'm not

exactly sure why that is in this case, but, in other cases people have
had more local clock derived sources than real sources, and, because
the reference implementation claims zero root delay and zero root

dispersion (because it assumes that the local clock is being disciplined
by some other means, rather than free running), an upstream local clock
can
have a very low apparent error band, so it can be quite difficult for
other
sources to fall within the same cluster.

The other basic problem is that downstream nodes don't receive any
indication
that they are disconnected from real time, whereas an alarm condition
would be signalled by a server without a local clock driver.

Note that using stratum 10 doesn't prevent these problems, it simply

stops nodes that more than about 2 hops downstream from having problems
from that particular local clock driver; it limits the area subject to
harm.

As to the urban myth. Whilst a lot of it is simply copy and paste
programming, I think there is a significant myth that, without the local
clock driver, the software clock will revert to its natural frequency,
when it loses all time sources.

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___________________________________________________________________

ANDREAS STIHL AG & Co. KG
Kommanditgesellschaft mit Sitz in Waiblingen, HRA 260269, Amtsgericht Stutt
gart

Persönlich haftende Gesellschafter: Hans Peter Stihl und STIHL Aktiengese
llschaft
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Dr. Peter Dürolf, Jürgen Steinhauser, Wolfgang Zahn
Vorsitzender des Aufsichtsrats der STIHL AG: Hans Peter Stihl

On 2007-12-07, [email]linux@stihl.de[/email] <linux@stihl.de> wrote:
[color=blue]
> you see no reason, why a ntp-client that does not serve its time to
> someone else should have a local clock configured?
> did i get this right?[/color]

The only reason to use the Undisciplined Local Clock (127.127.1.x) is on
an ntpd which must be able to serve time to others even when there are
no real time sources available.

The Undiciplined Local Clock is not a time source and does nothing to
keep ntpd synchronised.
[color=blue]
> does anyone of you have details regarding my original question:
> How can i find out which of the sanity-checks failed?[/color]

I don't think you can.
[color=blue]
> -----Original Message-----
> [---=| TOFU protection by t-prot: 100 lines snipped |=---][/color]

Oh, that's what you were replying to.

--
Steve Kostecke <kostecke@ntp.org>
NTP Public Services Project - [url]http://support.ntp.org/[/url]

Steve Kostecke wrote:[color=blue][color=green]
>> does anyone of you have details regarding my original question:
>> How can i find out which of the sanity-checks failed?[/color]
>
> I don't think you can.[/color]

if the sanity-checks failed it should put out a hex value containing the
errors detected. You then have to look at the code to see what those
bits mean. We shoulf be making this easier. What was the error that you
got? Sorry but I haven't been following this.

Danny

Danny Mayer wrote:[color=blue]
> Steve Kostecke wrote:[color=green][color=darkred]
>>> does anyone of you have details regarding my original question:
>>> How can i find out which of the sanity-checks failed?[/color]
>>
>> I don't think you can.[/color]
>
> if the sanity-checks failed it should put out a hex value containing the
> errors detected. You then have to look at the code to see what those
> bits mean. We shoulf be making this easier. What was the error that you
> got? Sorry but I haven't been following this.[/color]

Shouldn't this be visible via the flash bits displayed by
ntpq -c "rv <assId>" ?

I had asked the OP to post the output of the command. However, the output
was truncated. Here's a quote:[color=blue]
> ntpq> rv 8773
> assID?73 status 14 reach, 1 event, event_reach,
> srcadrmaster1, srcport 3, dstadr0.0.0.0,
> dstport 3, leap[/color]

The rest of the output which should be including the "flash" bits is missing
here.

Martin
--
Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont
Germany