topic Re: NTP issues in Operating System - HP-UX

NTP issues

Wouter Jagers — Thu, 27 Feb 2003 14:53:01 GMT

Hi,

Since a week or two I'm having troubles synchronizing NTP clients. Here's the situation:

The gateway machine on my local network acts as a 'local master': it syncs its time with some global ntp servers (out of my control), and all local machines sync their time with the gateway box.

(It's fair to mention that I suspect the problems to have started when this gateway machine had a crash.)

Now the clients will no longer sync, returning the well-known '27 Feb 14:55:01 ntpdate[1619]: no server suitable for synchronization found'.

A rundown from the current info I've gathered:

[client - root] ntpdate localmaster
27 Feb 15:31:27 ntpdate[1747]: no server suitable for synchronization found

--> hmmz.. the server is reachable and there's no firewall/router in between, so something must be wrong with the ntp service

[client - root] ntpdate -d localmaster
27 Feb 15:33:15 ntpdate[1760]: ntpdate version=3.5f; Thu Oct 23 13:37:24 PDT 1997 (6)
transmit(198.141.81.10)
receive(198.141.81.10)
transmit(198.141.81.10)
receive(198.141.81.10)
transmit(198.141.81.10)
receive(198.141.81.10)
transmit(198.141.81.10)
receive(198.141.81.10)
transmit(198.141.81.10)
server 198.141.81.10, port 123
stratum 16, precision -17, leap 11, trust 000
refid [0.0.0.0], delay 0.02675, dispersion 0.00014
transmitted 4, in filter 4
reference time: 00000000.00000000 Thu, Feb 7 2036 7:28:16.000
originate timestamp: c208a046.22987000 Thu, Feb 27 2003 15:33:42.135
transmit timestamp: c208a02b.aff2d000 Thu, Feb 27 2003 15:33:15.687
filter delay: 0.02791 0.02678 0.02675 0.02719
0.00000 0.00000 0.00000 0.00000
filter offset: 26.44726 26.44664 26.44664 26.44692
0.000000 0.000000 0.000000 0.000000
delay 0.02675, dispersion 0.00014
offset 26.446646

27 Feb 15:33:15 ntpdate[1760]: no server suitable for synchronization found

---> hmmz, the reference time seems to be all zero's, translating to februari 2036.. this is fishy !

[client - root] ntpq -p
remote refid st t when poll reach delay offset disp
==============================================================================
localmaster.gcc.dhl. 0.0.0.0 16 u 15 64 0 0.00 0.000 16000.0

---> hmmz, stratum 16 ? this would mean the server thinks it's unreliable/not synced ?!

[client - root] ntpq -c as
ind assID status conf reach auth condition last_event cnt
===========================================================
1 22308 8000 yes no

---> So I guess there's a definate problem with our local master.

[client - root] ntpq -p localmaster
remote refid st t when poll reach delay offset disp
==============================================================================
globalntp1 0.0.0.0 16 u - 64 0 0.00 0.000 16000.0
globalntp2 0.0.0.0 16 u - 64 0 0.00 0.000 16000.0

---> If I'm right, this reports the global servers to be stratus 16, too. However, I got confirmation from their admins saying "stratum 1, offset 0.006895, synch distance 0.00545, refid 'GPS'"

Shouls anyone know what to do/check next, that would be greatly appreciated !!

Thanks

Wouter

Re: NTP issues

John Bolene — Thu, 27 Feb 2003 15:57:41 GMT

sounds like your master cannot reach its time sources and has made itself unreliable

what does it show in syslog for localmaster? Is it OK with time sync?

I would cycle xntpd on the localmaster and check syslog to see if it connects with the globalmasters.

Re: NTP issues

Wouter Jagers — Fri, 28 Feb 2003 04:43:26 GMT

that's the strange thing.. the local master doesn't seem to notice anything being wrong.

It can reach the global servers perfectly, and it doesn't complain about a lack of servers suitable for syncing..

Some more outputs:

[localmaster - root] ntpq -p
remote refid st t when poll reach delay offset disp
==============================================================================
global1 0.0.0.0 16 u 13 64 0 0.00 0.000 16000.0
global2 0.0.0.0 16 u 13 64 0 0.00 0.000 16000.0

[localmaster - root] ntpq -p global1
remote refid st t when poll reach delay offset disp
==============================================================================
*LOCAL(0) .GPS. 0 - 16 64 377 0.00 0.000 3.37
+global2 .GPS. 1 - 42 64 377 147.50 0.250 4.82
+global3 .GPS. 1 - 36 64 377 194.75 0.125 4.84

So I stop xntpd and run a quick ntpdate -d global1:

28 Feb 05:30:50 ntpdate[25009]: ntpdate version=3.5f; Mon Jun 9 14:50:06 PDT 1997 (2)
transmit(198.141.252.66)
receive(198.141.252.66)
transmit(198.141.252.66)
receive(198.141.252.66)
transmit(198.141.252.66)
receive(198.141.252.66)
transmit(198.141.252.66)
receive(198.141.252.66)
transmit(198.141.252.66)
server 198.141.252.66, port 123
stratum 1, precision -9, leap 00, trust 000
refid [GPS], delay 0.04649, dispersion 0.00021
transmitted 4, in filter 4
reference time: c209647a.026e978d Fri, Feb 28 2003 5:30:50.009
originate timestamp: c209647a.efced916 Fri, Feb 28 2003 5:30:50.936
transmit timestamp: c209647a.880a0000 Fri, Feb 28 2003 5:30:50.531
filter delay: 0.04733 0.04677 0.04691 0.04649
0.00000 0.00000 0.00000 0.00000
filter offset: 0.308496 0.308076 0.308150 0.308382
0.000000 0.000000 0.000000 0.000000
delay 0.04649, dispersion 0.00021
offset 0.308382

28 Feb 05:30:50 ntpdate[25009]: adjust time server 198.141.252.66 offset 0.308382 sec

And when I start xntpd again:
[localmaster - root] /sbin/init.d/xntpd start
28 Feb 05:30:58 ntpdate[25032]: step time server 10.1.5.2 offset 0.308173 sec

Strange, aye ?

Re: NTP issues

T G Manikandan — Fri, 28 Feb 2003 04:55:01 GMT

Just check this doc

http://www1.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000063204535

Re: NTP issues

Wouter Jagers — Fri, 28 Feb 2003 07:32:14 GMT

Another strange thing: When I do an "ntpq -p" on my localmaster, I get this:

[localmaster - root] ntpq -p
remote refid st t when poll reach delay offset disp
==============================================================================
global1 0.0.0.0 16 u 22 64 0 0.00 0.000 16000.0
global2 0.0.0.0 16 u 21 64 0 0.00 0.000 16000.0

And when I do a "ntpq -p global2":

[localmaster - root] ntpq -p global2
remote refid st t when poll reach delay offset disp
==============================================================================
*LOCAL(0) .GPS. 0 - 30 64 377 0.00 0.000 3.35
+global1 .GPS. 1 - 11 64 377 147.50 0.250 4.82
+global3 .GPS. 1 - 20 64 377 208.25 -0.125 4.81

How come these global servers report stratus 16 to me and stratus 1 to other places ?

Re: NTP issues

John Bolene — Fri, 28 Feb 2003 14:05:29 GMT

that last output says ntpdate when you restarted xntpd?

there should be a xntpd display in syslog

maybe your xntpd points to ntpdate or something else is starting ntpdate like cron

the 2 kinds of ntp updates should not be running at the same time

Re: NTP issues

Wouter Jagers — Fri, 28 Feb 2003 16:10:47 GMT

If I'm right, xntpd always starts out by executing one ntpdate to step the time close enough to real time.
Then it starts using the daemon to make adjustments..

What I don't get is that my localmaster thinks global1 is at stratum 16, while global2 knows it's actually at stratum 1 ?!?

Re: NTP issues

Wouter Jagers — Fri, 28 Feb 2003 16:15:59 GMT

T.G: thanks for the link also, however I've read about every ntp configuration and troubleshooting doc online, including the RFC :-)

But inthere I only learn that the outputs I get are contradictory..

Re: NTP issues

John Bolene — Fri, 28 Feb 2003 19:10:45 GMT

-------
If I'm right, xntpd always starts out by executing one ntpdate to step the time close enough to real time.
Then it starts using the daemon to make adjustments..
--------

Not that I know of. If it is more than 1000 seconds off, it refuses to stay running.

On both my 10.20 and 11.0 machines when starting xntpd, I get

xntpd version=3.5f; Thu Oct 23 13:37:00 PDT 1997 (6)
tickadj = 625, tick = 10000, tvu_maxslew = 61875
precision = 10 usec

then after 5 minutes

synchronized to 172.20.4.82, stratum=4

What OS version are you running?

Re: NTP issues

Wouter Jagers — Fri, 28 Feb 2003 21:13:46 GMT

The master is a 10.20 ..

By the way I checked, and the init script for xntp first does a ntpdate -b and then starts xntpd

Re: NTP issues

Wouter Jagers — Fri, 28 Feb 2003 21:20:09 GMT

mine does all that, except getting synchronized after 5 minutes ;-)

Re: NTP issues

Edgar Avila — Tue, 10 Jun 2003 21:28:49 GMT

Look at http://www.ntp.org/ntpfaq/NTP-s-config.htm , after 6.2.6.2 .
Maybe you have congestion on your network. That could be the reason for the lack of '*' on your ntpq's indicating no suitable or alternate server.

Re: NTP issues

Wouter Jagers — Fri, 11 Jul 2003 20:26:57 GMT

Oops, did I not close up this one ? It was solved ages ago.. shame on me !

In short: I wrote the config file from scratch, and all problems were gone.

Thanks to all !