topic Re: Can Cisco ISE run normally without NTP server? in Network Access Control

Can Cisco ISE run normally without NTP server?

jj2048 — Tue, 09 Nov 2021 09:12:38 GMT

Upon discussing the requirements for installing Cisco ISE, our customer was not able to provide an NTP server address, as they don't have one yet.

As the title implies, can Cisco ISE run normally without an NTP server?

The deployment will be Two Standalone Nodes in HA.

What do you normally place on the NTP server address on the initial setup if this is possible?

Thank you in advance.

Re: Can Cisco ISE run normally without NTP server?

Mohammed al Baqari — Tue, 09 Nov 2021 10:11:01 GMT

Hi,

Installation will go through even if you put a dummy IP but you will run
into an endless number of problems. AD integration won't work because there
is a restriction on the allowed tick slips between ISE and AD clocks.
Certificates might expire which will interrupt ISE operation.

Short answer don't give your customer the option to install ISE without
NTP. In fact you should encourage them to use NTP as this is networking 101
for any organization. Its as simple as making internet routing polling
from pool.ntp.org and ISE sync from your router.

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Re: Can Cisco ISE run normally without NTP server?

Mark Elsen — Tue, 09 Nov 2021 10:43:49 GMT

>....don't give your customer the option to install ISE without NTP

Indeed!

Re: Can Cisco ISE run normally without NTP server?

thomas — Tue, 09 Nov 2021 14:31:11 GMT

Assuming you allow ISE Internet access, use time.nist.gov or pool.ntp.org

Re: Can Cisco ISE run normally without NTP server?

jj2048 — Tue, 09 Nov 2021 21:53:05 GMT

Thank you Mohammed for your explanation. This has been very helpful.
I will do recommend that they set up their NTP soon.

Re: Can Cisco ISE run normally without NTP server?

jj2048 — Tue, 09 Nov 2021 21:54:28 GMT

Thank you thomas,

I'll try this on our test bench.

I'll also ask what they use on their AD's as NTP server to match it with ISE for the time being.