NTP on Cisco Switches 1

[sogol]

Hi friends,

I have 10 Cisco 2960 switches that I want to synchronize their Clock with my domain controller As an NTP server.

I add the DC as my server but there is no change in the clock of the switch.

Any advice would be highly appreciated.

 

[burtsbees]

Post the NTP config---did you specify a source-interface?

Burt

 

[vipergg]

I know there are some issues getting cisco ntp to work with a Microsoft domain controller . I would do a search or try to find alternate internet ntp source like

http://tf.nist.gov/service/its.htm

 

[ADB100]

The NTP implementation in Windows (W32Time) is SNTP and you won't get a NTP client to sync from it. Some of the SOHO routers & autonomous AP's have SNTP clients and will happily sync with it, however the Catalyst 2960 (and all other IOS Catalysts) have 'proper' NTP clients and won't. It works the other way - i.e. a SNTP Client can sync with a NTP Server, but not the other way aroung.

I went through this a while ago and gave up. I ended up doing it the other way around - my last-hop router before the ISP link is configured to sync with three NTP servers on the internet, clients inside then sync from that router.
If you have a bigger infrastructure (i.e. lots of routers & switches) then it makes sense to deploy a hierarchal design with each site or distribution block providing NTP services downstream and syncing themselves off core or internet facing routers.

HTH

Andy

 

[VinceWhirlwind]

Make sure you award that last poster a star for his excellent advice.

 

[sogol]

Thanks Andy for your valuable information

In fact the things you said about SNTP and NTP are correct and I knew I have this problem,unfortunately I have no router at the moment in my network and all other devices are synchronizing themselves with DC as an internal NTP server.

My problem was because I know DC supports SNTP is there any way for my switches to sync their clock in LAN and now I have my answer.

Once I got routers then I will try your advice to configure them for updating their time from Internet NTP servers.

Thank you

 

[ADB100]

The 2960 could be your NTP server as it has a full NTP Server/Client.