NTP on Switch - Time gets decrement Automatically

[Fazal E Rasool Khan]

Good Day Everyone, 

I am working for one network which has no internet connectivity, only core switch is connected to some access switches. 
core switch is working as NTP server (ntp master command) and access switches are sync to this core switch.

I am facing problem with time, its getting decrement by 15 to 20 minutes repeatedly and i have to go and set the time again.

Is this the issue with stratum 8? How can i get accurate time all the time without sync to public NTP server. 

Also please advise what public NTP server (IP or domain) i should sync if i want to sync devices which has internet connectivity.

CORE-SW#sh ntp status
Clock is synchronized, stratum 8, reference is 127.127.7.1
nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**24
reference time is DC270D78.EE2B6AE4 (12:14:32.930 Mon Jan 16 2017)
clock offset is 0.0000 msec, root delay is 0.00 msec
root dispersion is 0.02 msec, peer dispersion is 0.02 msec

CORE-SW#sh ntp associations
address ref clock st when poll reach delay offset disp
*~127.127.7.1 127.127.7.1 7 61 64 377 0.0 0.00 0.0
* master (synced), # master (unsynced), + selected, - candidate, ~ configured

Thanks,

[Mark Malone]

yes cisco devices are not reliable as the main NTP server , over time it will keep varying off

You need to use a proper in-house server if not using a public NTP , like an Microsoft server , its not because its 8 more the fact the ntp server is a Cisco device  

Also please advise what public NTP server (IP or domain) i should sync if i want to sync devices which has internet connectivity.

This would be based on where your located , use this website to locate a server or pol near you that's reliable

http://www.pool.ntp.org/vendors.html

[Paul Chapman]

Hi -

It is actually possible to obtain accurate time without an internet connection.  Several companies sell systems that obtain time via antenna either from GPS or other radio broadcasts.  This would allow you to maintain your isolated network and have accurate time.

A quick google search found this company:

https://www.endruntechnologies.com/ntp-server.htm

I have never used this product, but it gives you an idea of what is out there.

PSC

[Fazal E Rasool Khan]

Thanks Paul and Mark for your inputs. 

Paul just one question. Is this service for free or customer need to pay for this 

This would be based on where your located , use this website to locate a server or pol near you that's reliable

http://www.pool.ntp.org/vendors.html

[Mark Malone]

Hi

you asked Paul the question but added my link , if your asking about using the NTP pool website its completely free , if its regarding the GPS information Paul can answer that I wasn't aware of that system

[Fazal E Rasool Khan]

Thanks Mark. It was Typo mistake but i was pointing that question to you. 

Appreciated guys for your support.

[Paul Chapman]

Hi Fazal -

Appliances from the various vendors have their own costs, which you can negotiate with them.  Once installed, there's no "subscription" cost for receiving time from GPS satellites or radio.

PSC