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New Member

NTP Question

NTP configuration does not seem very clear.

I need to make several of my WAN routers NTP Servers so that they can provide NTP to Windows Servers on the local LAN

I also need to make my WAN routers sync up with my core router. I believe the NTP peer command will do this but may be wrong.

Can someone please advise?




Re: NTP Question

I am posting a sample config for your quick reference. Your config should look something similar to thiis :


Set the timezone and enable the router to act as a valid time source.


clock timezone

clock calendar-valid




ntp master 5


!your router will derive its clock from the Unix server. And, NTP is used to

! update the hardware calendar built-in.

!ntp server

ntp update-calendar


On remote routers:



! Derive clock information from your router.


ntp server

Use "show ntp status" command to check clock synchronization.

New Member

Re: NTP Question

I don't know what IOS this is for, but on 12.3(13),

on a 2651 or 3745,

there's no such command I can find as:

clock calendar-valid, or any other calendar command that I can see. Is this only for a 7204?

Is there any way to save the calendar on the

smaller routers?

Hall of Fame Super Silver

Re: NTP Question

For the WAN router to sync with the core router you can use NTP PEER or use NTP SERVER. The PEER command implies two way sharing of time information. The SERVER command implies that one device learns time from the other but is not reciprocal. In the situation you describe I believe that SERVER would be the more appropriate option.

Once your WAN routers have learned authoritative time they can provide time to the Windows Servers.(either the Windows Servers can query the WAN router or the WAN router can be configured with NTP BROADCAST on the LAN interface to send NTP information).

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