cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Announcements
Popup Hotspot Using ISR 1000 with WiFi/LTE for Teleworkers and Micro Branchesr
14295
Views
5
Helpful
5
Replies
Highlighted
Beginner

3560 As NTP Server

Switch: WS-C3560-48PS-E

IOS: (C3560-IPSERVICESK9-M), Version 12.2(53)SE2

I have the above switch running at a small site; it is configured as the default gateway (10.x.x.1 - has multiple VLANs) and also currently gets its own time from an NTP server across the WAN.

How can I configure this switch so that hosts in this site can get their NTP from it?

Seems I have to configure interfaces, either physical or VLANs, with...

ntp broadcast

...but then don't the hosts have to be able to receive NTP broadcasts?  I don't necessarily know what the capabilities of the various hosts are so I can't relay on this functionality it seems.  I want the hosts to have whichever 10.x.x.1 set and actively query it for NTP.

Thanks,

jdlampard

Everyone's tags (3)
5 REPLIES 5
Highlighted
Advisor

3560 As NTP Server

Hi,

just use the command ntp master on the switch and then put the ip address of the switch on your ntp clients.

Regards.

Alain.

Don't forget to rate helpful posts.
Highlighted
Hall of Fame Expert

3560 As NTP Server

Configure the hosts to get their time from the same device you are getting timing for your switch, because

The switch does not have a hardware-supported  clock and cannot function as an NTP master clock to which peers  synchronize themselves when an external NTP source is not available. The  switch also has no hardware support for a calendar. As a result, the  ntp update-calendar and the ntp master global configuration commands are not available.

http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.1_19_ea1/configuration/guide/swadmin.html#wp1053923

HTH

Highlighted
Advisor

3560 As NTP Server

Hi Reza,

I didn't know this fact, thanks for info.

Regards.

Alain.

Don't forget to rate helpful posts.
Highlighted
Hall of Fame Community Legend

3560 As NTP Server

I agree with Reza.  I wouldn't configure Cisco appliance as an authoritative NTP server.

If you have Windows servers, you can configure them to be an authoritative NTP server.

How to configure an authoritative time server in Windows XP

http://support.microsoft.com/kb/314054

How to configure an authoritative time server in Windows Server

http://support.microsoft.com/kb/816042

How to configure an authoritative time server in Windows 2000

http://support.microsoft.com/kb/216734

The Cisco appliance don't really have a "clock" per se.  They have a battery operated internal clock and it's not synchronized.  However, if you let the Cisco appliance synchronize to an authoritative source and use this same appliance to dish out the NTP details, then it's the way to go.  I know I have implemented this type of system in several networks.

Highlighted
Beginner

You cannnot configure a 3560

You cannnot configure a 3560 Switch as a NTP Server (Master) itself. It's not supported. Even ntp per interface commands do not work. This is what Cisco says about this: 

The switch does not have a hardware-supported clock and cannot function as an NTP master clock to which peers synchronize themselves when an external NTP source is not available. The switch also has no hardware support for a calendar. As a result, the ntp update-calendar and the ntp master global configuration commands are not available.

See the link here: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_55_se/configuration/guide/3560_scg/swadmin.html

CreatePlease to create content
Content for Community-Ad