Edison Ortiz Wed, 08/08/2007 - 05:54
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I don't recommend designating a Cisco router or switch as NTP server. I recommend using a NTP server in the internet and point these devices to it.

These 51 devices have IP connectivity to the internet ?

If so, just enter

ntp server [ip address]

in config mode and they will sync with the NTP server. You want may to configure the timezone and offset values as need

clock timezone

is the command you need.

For a list of public NTP servers, please visit ntp.org


Pavel Bykov Wed, 08/08/2007 - 06:15
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Don't forget to configure timezone, sou all your devices switch to summer-time and back automatically without problems. Depending on your NTP server, it could be UTC, so you should set up offset.

Commands are:

clock timezone NAME OFFSET_FROM_UTC (1 for central European for example)

clock summer-time NAME recurring last Sun Mar 2:00 last Sun Oct 3:00 (times when to switch to summer time and back)

NTP server setup is easy:

"ntp server x.x.x.x" command is the most important command, and it tells device where to get the time from. Has to be reachable by IP. Could be a server in your network, that synchronizes to internet NTP. Or it could be a PC with NTP server functionality (see manuals for your operating systems). Or it can be another Cisco device.

You can secure your NTP a bit by using authentication. Update calendar, define update intervals and so on. Everything optional.

Like this:

ntp authentication-key 1 some_password

ntp authenticate

ntp trusted-key 1

ntp clock-period 17179927

ntp update-calendar

ntp server x.x.x.x key 1

ntp server y.y.y.y key 1

You can have as many servers as you want, but don't overdo it.

upendra07 Fri, 08/10/2007 - 09:14
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Can i use windows xp for ntp server

How can i do

Richard Burts Fri, 08/10/2007 - 09:37
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If you install some application/service you could use a Windows XP machine as the NTP server. But the Windows Time service is not NTP and will not serve as an NTP server.

In the previous post was this comment:

Depending on your NTP server, it could be UTC

actually NTP is always UTC. So it is helpful to configure the clock timezone offset so the clock will look like local time.



dphills18 Mon, 03/17/2008 - 21:37
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can you recommend a good ntp server application.

Richard Burts Mon, 03/17/2008 - 22:26
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I have not used it but I have heard some good things about the NTP implementation by Meinberg for Windows. Additional information is probably available from this link:




dphills18 Tue, 03/18/2008 - 10:10
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I got everything working. Thanks for all your input. I used the app that was suggested. Eventually, I will go to NTP Appliance. Better security.

I had to do a couple additional things to make it work though:



I changed Enabled from 0 to 1.


LocalClockDispersion Entry

Change from default of 10 to 1

hobbe Tue, 03/18/2008 - 09:15
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I have been using a Meinberg hardware device for my NTP needs and I like it alot.

It uses the GPS signal to get the time and if something happens to the GPS signal it has a internal clock that will hold time within specified parameters for atleast 10 days.

This solution is alot better than using any server desktop or network machine as a NTP server since the device has a better crystal than any "normal" server and it is constructed to do what it does and it does it good.

Good luck


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