Subject: Re: ntpq regression (?)
To: Jukka Salmi <email@example.com>
From: Frank Kardel <firstname.lastname@example.org>
Date: 06/18/2006 18:11:05
Jukka Salmi wrote:
>Jukka Salmi --> current-users (2006-06-15 20:56:32 +0200):
>>since upgrading ntpd (from 4.2.0-r to 4.2.2-o) `ntpq -pn' reports:
>>$ ntpq -pn
>> remote refid st t when poll reach delay offset jitter
>>#126.96.36.199 188.8.131.52 3 u 26 64 377 0.204 87.820 10.383
>> 184.108.40.206 220.127.116.11 4 u 11 64 377 0.226 83.891 7.109
>>The `selected' peer ('#') used to be a `sys.peer' ('*'), and the
>>`reject' peer (' ') used to be a `candidat' ('+').
>After restarting ntpd I see
>$ ntpq -pn
> remote refid st t when poll reach delay offset jitter
>*18.104.22.168 22.214.171.124 3 u 1 64 37 0.206 0.129 7.519
>+126.96.36.199 188.8.131.52 4 u 1 64 37 0.184 -2.813 5.601
>However, after the next ntpd restart `ntpq -pn' output was again as
>reported in the first post...
This is not an ntpq regression but a visible effect of the minsane
option. The default distributed in NetBSD is 2. That means at least 2
must be configured (and be usable and be close to each other).
But this is not suffcient because several tests are performed that can
sources from the selection list before the minsane limit is checked.
Checks are for synchronisation status, stratum, synchronisation
distance, loop, reachability,
Given the data above (with the #) the falseticker detection probably had
its veto here.
Then we are left with one 'usable' peer for the remaining algorithms.
Thus not a chance
for synchronisation to succeed. With this configuration it'll only work
if the two peers are
sufficiently close to each other (see the example above).
So we are looking at a problematic configuration (possibly by default
This configuration will only work when both sources are usable and agree
with each other.
There are two ways to fix this:
1) comment out "tos minsane 2" or set it to one (ntp default for
historical reasons to allow
backward compatibility and faster synchronisation but vales below 4
disable byzantine agreement
2) set "tos minsane 4 (or greater)" for working byzantine agreement and
configure *at least*
that number of synchronisation sources.
I agree that "tos minsane 2" can be very confusing especially when there
is no hint on how many
sync sources to configure.