Hello everybody,
We're facing a problem, that we have ntp-servers with synchronized
system time by an external clock. The ntp servers are now distributing
the (synchronized) time to all other servers. This works well at the
first time, the ntp-servers are seen as peers on most of the clients,
sanity checks are passed. But it seems that after a while the ntp
clients are going to reject all their servers due to not passing the
sanity checks, which means, that the time is not synchronized any more
on those systems.
The paper "Using NTP to Control and Synchronize System Clocks - Part
III" by Sun blueprints Online says in NTP Algorithms/Sanity Checks, step
6: "...that servers, which are not connected to a root time source, will
be ignored." So is this now the reason why the ntpclients are going to
reject the servers or am I missing something? And if so: is there any
chance to get the system time (which is synchronized - see below)
distributed via NTP?
Some words to the setup:
Four ntp-servers ntpserver[1-4] are synchronized via serial lines to a
single external timesource. On these system a deamon (which does mainly
other things) adjusts the system time according to these serial signals
at least every 10 minutes. I can't switch to other / external ntp
servers, since I need this one and only time (broadcast environment) and
the servers are sitting on an isolated network. The external device is a
LTC timecode converted by a Miranda Littlered, the serial signals are
processed by a deamon, which is exclusively connected to the serial
port.
ntpserver1 8# more /etc/ntp.conf
# Generic ntp.conf file
#
# See documentation for more options
#
# add as many server as required
server 127.127.1.0
fudge 127.127.1.0 stratum 0 refid LTC1
broadcast 192.168.58.255 ttl 2
driftfile /etc/ntp.drift
# don't set local clock
disable ntp
This last setting is necessary to disable the setting of the system
clock by ntp, the system time of the ntp-server shall exclusively set by
the deamon.
The ntp clients listen to only these servers.
ntpclient 14# more /etc/ntp.conf
# Generic ntp.conf file
#
# See documentation for more options
#
# add as many server as required
server ntpserver1 prefer
server ntpserver2
server ntpserver3
server ntpserver4
driftfile /etc/ntp.drift
# monitor no
# authenticate no
#
broadcastclient yes
# multicastclient
Especially if the ntp deamon is started on one ntp-server, this server
is picked up as a peer (or at least a candidate).
ntpclient 3# ntpq
ntpq> pe
remote refid st t when poll reach delay offset
jitter
========================================================================
======
*ntpserver1 .LTC1. 1 u 20 64 377 0.502 -32.966
0.258
+ntpserver2 .LTC1. 1 u 25 64 377 0.441 -32.922
0.155
+ntpserver3 .LTC1. 1 u 51 64 377 0.511 -33.044
0.224
-ntpserver4 .LTC1. 1 u 11 64 377 0.431 -33.129
0.098
ntpq> ass
ind assID status conf reach auth condition last_event cnt
===========================================================
1 49084 96f4 yes yes none sys.peer reachable 15
2 49085 94f4 yes yes none candidat reachable 15
3 49086 94f4 yes yes none candidat reachable 15
4 49087 93f4 yes yes none outlyer reachable 15
ntpq> readvar
status=06f4 leap_none, sync_ntp, 15 events, event_peer/strat_chg,
version="ntpd [EMAIL PROTECTED] Wed Jan 19 14:18:56 PST 2005 (1)",
processor="IP35", system="IRIX646.5", leap=00, stratum=2, precision=-18,
rootdelay=0.502, rootdispersion=837.489, peer=49084,
refid=ntpserver1,
reftime=c92252a9.504955b4 Thu, Dec 7 2006 9:43:21.313, poll=6,
clock=c92252d4.4004102f Thu, Dec 7 2006 9:44:04.250, state=4,
offset=-32.966, frequency=195.127, jitter=0.178, stability=0.127
ntpq> readvar 49084
status=96f4 reach, conf, sel_sys.peer, 15 events, event_reach,
srcadr=ntpserver1, srcport=123, dstadr=<ntpclient>,
dstport=123, leap=00, stratum=1, precision=-18, rootdelay=0.000,
rootdispersion=827.820, refid=LTC1, reach=377, unreach=0, hmode=3,
pmode=4, hpoll=6, ppoll=6, flash=00 ok, keyid=0, offset=-32.883,
delay=0.471, dispersion=0.943, jitter=0.083,
reftime=c92252b3.f02f0e0a Thu, Dec 7 2006 9:43:31.938,
org=c92252ea.4a8997c3 Thu, Dec 7 2006 9:44:26.291,
rec=c92252ea.53041461 Thu, Dec 7 2006 9:44:26.324,
xmt=c92252ea.52e3821a Thu, Dec 7 2006 9:44:26.323,
filtdelay= 0.47 0.50 0.51 0.48 0.48 0.51 0.49
0.51,
filtoffset= -32.88 -32.97 -33.22 -33.26 -33.46 -33.51 -33.67
-33.86,
filtdisp= 0.01 0.98 1.96 2.90 3.86 4.82 5.77
6.73
ntpq>
After some time the servers are going to be rejected, although the
sanity checks are passed. The associations are going to be
ntpclient 2# ntpq
ntpq> pe
remote refid st t when poll reach delay offset
jitter
========================================================================
======
ntpserver1 .LTC1. 1 u 44 64 377 0.033 88339.7
28.006
ntpserver2 .LTC1. 1 u 48 64 377 0.064 88338.0
27.700
ntpserver3 .LTC1. 1 u 59 64 377 0.059 88333.4
27.613
ntpq> ass
ind assID status conf reach auth condition last_event cnt
===========================================================
1 60236 9034 yes yes none reject reachable 3
2 60237 9034 yes yes none reject reachable 3
3 60238 9034 yes yes none reject reachable 3
ntpq> readvar
status=00f4 leap_none, sync_unspec, 15 events, event_peer/strat_chg,
version="ntpd [EMAIL PROTECTED] Wed Jan 19 14:18:56 PST 2005 (1)",
processor="IP35", system="IRIX646.5", leap=00, stratum=16,
precision=-18, rootdelay=0.442, rootdispersion=4115.402, peer=0,
refid=ntpserver1,
reftime=c9249b12.cc18c5c9 Sat, Dec 9 2006 3:16:50.797, poll=4,
clock=c927cc57.727e846a Mon, Dec 11 2006 13:23:51.447, state=2,
offset=0.000, frequency=-259.475, jitter=13.014, stability=213.142
(Note: I've removed the falseticker here)
Thanks for help,
Dirk
_______________________________________________________________________
Dirk Langner Silex Media
GmbH
E-Mail: [EMAIL PROTECTED] Tel.: +49 (0) 89 / 45 125 49-14
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