NTP update on the 3850

[rasmus.elmholt]

Hi

I have a 3850 switch with NTP configured. The connection to the NTP server was disconnected briefly but after the reconnect NTP hasn't syncroniced.

It would probably start to work if i remove and add the ntp server statement againt. But are there any ways to get this to work again without reconfiguring the switch(removing and adding the ntp server)

Switch Ports Model SW Version SW Image Mode
------ ----- ----- ---------- ---------- ----
* 1 32 WS-C3850-24T 03.06.03.E cat3k_caa-universalk9 BUNDLE

SWITCH#show clock
.09:22:29.466 Greenl Thu Sep 15 2016
SWITCH#show ntp ass

address ref clock st when poll reach delay offset disp
~172.20.5.49 .INIT. 16 127137 1024 0 0.000 0.000 15937.
172.28.10.44 .INIT. 16 1323 1024 0 0.000 0.000 16000.
* sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured
SWITCH#show ntp status
Clock is unsynchronized, stratum 16, no reference clock
nominal freq is 250.0000 Hz, actual freq is 250.0050 Hz, precision is 2**10
ntp uptime is 2378908500 (1/100 of seconds), resolution is 4000
reference time is DB831257.C624DF50 (22:03:35.774 Greenl Tue Sep 13 2016)
clock offset is 0.0000 msec, root delay is 0.00 msec
root dispersion is 1.81 msec, peer dispersion is 0.00 msec
loopfilter state is 'CTRL' (Normal Controlled Loop), drift is -0.000020078 s/s
system poll interval is 64, last update was 127142 sec ago.
SWITCH#

[Georg Pauwen]

Hello,

try the 'clock read-calendar' exec command, that should resync your NTP.

HTH

[rasmus.elmholt]

Hi

The command does not exist:

SWITCH#clock read-calendar
^
% Invalid input detected at '^' marker.

SWITCH#clock ?
set Set the time and date

[Georg Pauwen]

Hello,

not good. Can you check if the following command is available from global config mode ?

SWITCH(config)#ntp update-calendar

[rasmus.elmholt]

Hi

It is not.

[Georg Pauwen]

Hi,

I have searched all around for an appropriate command in that release, it doesn't seem to be there. The most extensive document I could find regarding NTP on the 3850 switch is the one below, maybe it is to some use for you...

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/bsm/configuration/xe-3se/3850/bsm-xe-3se-3850-book.pdf

[rasmus.elmholt]

I have looked at that one as well, and it doesn't seems there are any reinitialization commands.

Thanks

[Leo Laohoo]

~172.20.5.49 .INIT. 16 127137 1024 0 0.000 0.000 15937.
172.28.10.44 .INIT. 16 1323 1024 0 0.000 0.000 16000.

The NTP configuration of the switch points to these two hosts.  Please describe what they are?  Are they windows-based machine?

[Richard Burts · Accepted solution]

The original post seems to suggest that NTP was working. But I agree with Leo that a starting place would be to clarify whether NTP was working successfully with the current configuration.

The fact that the reference clock shows as INIT indicates that this switch has not successfully communicated with the NTP servers. So perhaps another step in troubleshooting would be to verify connectivity to the servers.

HTH

Rick

[rasmus.elmholt]

The server didn't reply on the NTP packets. The SP moved us to a new switch where NTP wasn't supported on VRFs by default.

Thanks to everyone for their replies.

[Richard Burts]

Thanks for posting back to the forum to let us know that the issue has been resolved and what the issue was. It is interesting to know that the cause was the SP moved your gear.

HTH

Rick

[rasmus.elmholt]

Hi

Hardware upgrade in the backbone.

So now were connected to a new and more powerfull PE.

[Leo Laohoo]

The server didn't reply on the NTP packets.

"server"????  As in a Windows-based server?

Windows do NOT support NTP/SNTP standards.  This is why Cisco appliances will never be able to get NTP/SNTP synchronized with a Windows-based system.

[rasmus.elmholt]

NTP Server*

Years ago I always used the MS ADDC as a NTP server for my network devices, but in recent updates of windows server the feature is broken as you mention.

So now I am using ntp.org og ntp.ubuntu.com as external NTP servers.

[rasmus.elmholt]

Is it a Cisco Router