[ntp:questions] poll interval - Clarification! - RFC compliancequestion

Anton Persson A anton.a.persson at ericsson.com
Tue Jun 17 08:41:55 UTC 2008


Since I was still a bit too vague in my last post i want to clarify

What we are using is the Red Hat ntp package, for ntp v 4.2.4. But
we have removed the ntp-4.2.4p0-sleep.patch since it caused a
segmentation fault.
(This has been reported to one of the red hat mailing lists, however I
yet to receive any reply from them about it..)

We have, however, in the /etc/ntp.conf file explicitly stated that the
should communicate using NTP v3. What this means is that ntpd says, to
to the
server it is synching with, that it uses NTP v3 (even though it is
capable of v4.)
I have no idea how this affects the different state machines running
inside the
ntpd, just that the packet it sends out on the network state v3 instead
of the
default v4. The reasons for this is requirements from a legacy project
which we
are communicating with..

The poll interval is 64 to 1024, seconds. ntpd starts up, locks on
target, stays
synchronized for a while, then we pull the plug. The poll interval is at
this time
still 64 seconds, how long should it take to step up the interval to 128
seconds for
a completely failed link?

This is with the redhat version of ntp as said above, and with no other
configuration than: 

server     # local clock
fudge stratum 10

driftfile /var/lib/ntp/drift

server version 3

ntpd is started with the following options (-g is because we have no RTC
and so the offset we start with is very very large..):

ntpd -u ntp:ntp -p /var/run/ntpd.pid -g

   Best regards,

-----Original Message-----
From: questions-bounces+anton.a.persson=ericsson.com at lists.ntp.org
[mailto:questions-bounces+anton.a.persson=ericsson.com at lists.ntp.org] On
Behalf Of Unruh
Sent: den 16 juni 2008 19:30
To: questions at lists.ntp.org
Subject: Re: [ntp:questions] poll interval - Clarification! - RFC

anton.a.persson at ericsson.com (Anton Persson A) writes:


>I want to clarify one important issue since this discussion took a 
>completely different turn that the technical one I was looking for.

>We are NOT implementing the NTP protocol, we are using the reference 
>implementation straight out of <unnamed commercial embedded Linux
>distribution>. I thought that was clear from the syntax of
>my configuration and the fact that we use ntpq/ntpdc... ;-)

The distros may change ntp. Ie, they are usually NOT the reference

>The question I had was, in other words, should I expect the poll
>interval reported by ntpq to increase when using ntpd 4.2.4? And,


>if it is to be expected, how fast should it increase? (This is
>in the case when ntpd is in synchronization with a server and
>the communication breaks down, the server is "down".) (The
>reason I named NTP v3 is that we have configured the daemon
>to use NTP v3 explicitly..)

Sorry, you told us that you are using some unknown version from some
unknown distribution, and then ask about NTPV3. Is the implimentation an
implimentation of the v3 or v4? Tell us the version number and the
Why are you so coy about the details?

I think that on a lost lock, ntp first decreases the poll interval, on
theory that the loss was temporary, and that the next time it will be
there. If that does not work, then the poll interval is increased. 
But I think the min and max poll are still honoured. Ie with a maxpoll
10 it does not wait for 8 days (poll 16)  before trying again.

>I just want to say that I don't mind the license discussion, it's
>an important subject to discuss. However; I'm biased and I really
>prefer the GPL.. ;-)

The license is far less restrictive than GPL. 

>    Best regards, Anton

>-----Original Message-----
>From: questions-bounces+anton.a.persson=ericsson.com at lists.ntp.org
>[mailto:questions-bounces+anton.a.persson=ericsson.com at lists.ntp.org]
>Behalf Of Harlan Stenn
>Sent: den 13 juni 2008 20:44
>To: questions at lists.ntp.org
>Subject: Re: poll interval - RFC compliance question


>You are familiar with the draft NTPv4 spec, which includes SNTP, right?

>More info at http://support.ntp.org/IETF/WebHome .

>Several of your questions would be useful on the IETF NTP workgroup
>mailing list, and would be useful and interesting topics for the
>or Dev areas of http://support.ntp.org .

>Finally, I encourage you and everybody else who is working for a
>that has an interest in NTP to get your company to join the the NTP
>Forum, http://ntpforum.isc.org .  I am happy to do whatever I can to
>make membership in the NTP Forum a valuable experience.
>Harlan Stenn <stenn at ntp.org>
>http://ntpforum.isc.org  - be a member!

>questions mailing list
>questions at lists.ntp.org

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