Re: [chrony-users] chrony and ntpd xleave interoperability

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On Tue, Jan 23, 2018 at 02:44:56PM +0100, FUSTE Emmanuel wrote:
> Le 23/01/2018 à 13:00, Miroslav Lichvar a écrit :
> > With the current versions, if you can avoid the issue with
> > unsynchronized sources, they should interoperate, at least when their
> > polling intervals match. If it doesn't work for you, I'd like to see a
> > tcpdump output.
> Ok. I fixed min/max polling interval to 5 for testing purpose.
> Then I first restarted chrony. Wait for it to sync on a online source.
> Then restarted ntp and take capture.
> Will send you all the datas
> 
> NTP is stuck in unreachable state
> Chrony is stuck with only one valid RX.

Ok. I can reproduce this problem. It seems ntpd doesn't update its
state in the interleaved mode when it receives a packet with an
unexpected origin timestamp. There was a similar issue fixed for the
basic mode few ntp releases ago:
https://bugs.ntp.org/show_bug.cgi?id=2952

As chronyd doesn't switch to the interleaved mode until it's receiving
valid responses and ntpd doesn't accept responses in the basic mode,
they are stuck waiting forever on each other.

A similar thing seem to happen when trying to use the interleaved mode
between two 4.2.8p10 ntpds. You said it worked for you before, so I
assume one of the ntpds was an older version which didn't have this
bug?

-- 
Miroslav Lichvar

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