CUCM 11.5 installation NTP server inaccessible

[AR15]

I've tried all accessible NTP servers from NTP.org from Stratum 1 and 2. My NTP server is still inaccessible by CUCM installation. My home router uses pool.ntp.org for its NTP server but the CUCM won't even detect that. Any recommendations?

[C_Noble]

I am assuming you are setting up CUCM in your home lab.

You can configure a NTP server on a router instead of reaching out to a public NTP server.

If you do not have a Cisco router available, are you sure you have connectivity to the IP addresses at pool.ntp.org ?

[AR15]

Well I'm able to ping pool.ntp.org

[C_Noble]

I cannot view your screenshots from my work computer. I have not used pool.ntp.org before. Do those NTP servers require authentication? Please ensure that you resolve the pool.ntp.org name via nslookup and then ensure you can ping those IP addresses sourced from the CUCM default gateway. Can you provide some more information about your setup? Is this for a lab or production? If you have a router available and this is not in production I can provide you the link for NTP Server setup.

[AR15]

I'm able to resolve them by nslookup. All the NTP servers I made sure were open access and not restricted. All the pings successful sourced from the same network range that CUCM is configured for.

Setup:

VMware Fusion setup with bootable iso.

Redhat 5 64bit

2 CPU processor

80 GB HD

6 MB memory

I'm running all this from my OSX Catalina.

[C_Noble]

I will run a test on pool.ntp.org from my home lab this afternoon and let you know the results.

[C_Noble]

You can confirm if your NTP traffic is leaving your workstation with Wireshark if you still want to use pool.ntp.org. Are you sure that your virtual machine can route out of the virtual environment on your workstation? I would check to ensure your network adapters on your virtualization software are confirured properly.

Also, it sounds like you do not have a Cisco router available to use as a NTP server. I suggest you look into GNS3, load a Cisco router OS into the program and then create a connection from that virtual instance of the router back to your PC. There is plenty of documentation on the internet for GNS3 setup if you are unfamiliar. Long term, this will enable you to build much more robust networks on your PC as well.

Here is the link for NTP configuration on Cisco routers : https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/bsm/configuration/15-2mt/bsm-time-calendar-set.html#GUID-A1071998-72BE-4F2E-8BC0-3A9FDC5D67EE
You will have to configure the system clock and use that as the authoritative time source. You would not do this in production, but for lab purposes it works just fine.

[Amine Nouasri]

You can use your local PC as an internal NTP server to get the install going. I have done it in Windows and I am pretty sure you can find a procedure for Mac in the Internet.

[AR15]

My mac gets time from time.apple.com and I've tried all the IPs listed below. Still shows inaccessible.

time.apple.com canonical name = time-osx.g.aaplimg.com.

Name: time-osx.g.aaplimg.com

Address: 17.253.6.125

Name: time-osx.g.aaplimg.com

Address: 17.253.24.125

Name: time-osx.g.aaplimg.com

Address: 17.253.24.253

Name: time-osx.g.aaplimg.com

Address: 17.253.2.125

Name: time-osx.g.aaplimg.com

Address: 17.253.2.253

[Amine Nouasri]

Yes, but I meant to configure the ntpd service on you Mac and point your CUCM install to use your local PC as an NTP server. This is in order to complete the install. After that, you can simply adjust the time manually from the CLI or troubleshoot further your NTP issue.

[AR15]

I will try that and update you. Thanks for your suggestion. From what I found so far, my ISP provider blocks UDP port 123. This maybe the reason why all NTP servers show inaccessible. 

[AR15 · Accepted solution]

Thank you guys. I figured out the problem. I was using my Netgear Orbi routers as router and a satellite and to be able to utilize all the features it has to offer. I was only using ISP router as passthrough device. Once i converted both Orbis into satellite and used ISP router as the main router. I'm able to find accessible NTP server. Somehow it was blocking the connection to the NTP server even though I was able to ping it.