09-22-2008 07:33 AM - edited 03-06-2019 01:30 AM
I have a Linux NTP server that I use to
synchronize for all of my routers and switches. I would like routers and switches to poll the NTP servers every
60 seconds. How do I go about doing that
on Routers and Switches?
On my Linux servers, I use "ntpdate 192.168.1.1" and crontab this to run
every 60 seconds. I would like to do the
same thing on Cisco IOS routers and switches. How do I go about accomplishing
this?
Thanks.
09-22-2008 07:45 AM
http://www.cisco.com/en/US/docs/switches/lan/catalyst4000/7.6/configuration/guide/ntp.html
Hope that helps
Per Rick, I grabbed the wrong link. Here's configuring in IOS.
http://www.cisco.com/en/US/docs/ios/12_1/configfun/configuration/guide/fcd303.html#wp1001170
09-22-2008 08:03 AM
David
The link supplied by Collin is a nice description of how to configure NTP on Catalyst switches running CatOS. But I do not see anything in it about controlling the frequency with which the switch will querry the server. And in fact I am not aware of anything that would control the frequency with which the switch will querry the server. In Cisco's implementation the Cisco device acting as client will querry the server every 64 seconds in the beginning. And as the client receives responses from the server and the relationship stabilizes and the client believes that it is accurate, the client will querry at longer and longer intervals. I am not aware of a config option that would change this behavior.
HTH
Rick
09-22-2008 08:01 AM
In global config mode you can use:
ntp server xxx.xxx.xxx.xxx
You need to make sure that the actual clock on the router/switch is set as close as possible, or the clock never syncs.
This is done in enable mode:
clock set 12:00:00 Sep 22 2008
HTH
John
09-22-2008 08:06 AM
Hi,
I do not think we can define poll interval on Cisco routers and switches , it changes dynamically from 64 seconds to 1024 seconds .
From the link below:Network Time Protocol: Best Practices White Paper
"
An NTP client makes a transaction with its server over its polling interval (from 64 to 1024 seconds) which dynamically changes over time depending on the network conditions between the NTP server and the client. No more than one NTP transaction per minute is needed to synchronize two machines."
http://www.cisco.com/en/US/tech/tk869/tk769/technologies_white_paper09186a0080117070.shtml
HTH
Saju
09-22-2008 08:10 AM
I misread the question. No, the polling frequency can't be changed.
HTH
John
09-22-2008 08:49 AM
Thank you everyone for the feedback. I know how
to configure NTP on Cisco routers and switches.
My question has to do with controlling the
frequency of the routers and switches to poll
the NTP servers like "ntpdate 4.2.2.2" on Linux
servers. Is this something that can be done?
Thanks.
09-22-2008 09:06 AM
David
I thought that my answer:"I am not aware of a config option that would change this behavior" and the very similar answer from Saju were pretty clear that you can not change the poll interval.
HTH
Rick
09-22-2008 09:21 AM
I was hoping that this may be a "new" feature
in IOS 12.4(T) or something like that.
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