Windows Server 2016 VM as Cisco Call Manager NTP Server Issues


I'm having issues completing the Cisco Call Manager setup because it doesn't recognize my Windows 2016 PDC's NTP service.

Both are VMs on different ESXi hosts.
I can ping the Call Manager VM.
The switch recognizes the PDC as a Stratum 2 source.
My Windows domain and CM are on separate VLANs on this switch.
There's no access to the Internet or any other external source.

I did research and apparently the fact that the PDC is a VM can cause issue, but surely there's a solution.

Thanks in advance!
Michael LPr. SysadminAsked:
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Cliff GaliherCommented:
I don't know where you read that the NTP source being a VM would be an issue, but that isn't true. It can cause the VMs clock to skew, sure. But that is a different issue from not being recognized.  That it is the PDCe role holder isn't relevant in this scenario.

How are you routing traffic between VLANs?  That's my first suspicion as the problem given your description.
Michael LPr. SysadminAuthor Commented:
VLANs use tagging, if that answers your question. My knowledge of the configuration is limited, but I can get with the network guy for more answers.
Cliff GaliherCommented:
Think of a VLAN as a completely separate LAN (that's why its a "virtual" LAN.)

One VLAN cannot talk to another unless there is something routing traffic between the two.  You want to connect to the internet?  You need a router.  Same basic concept here.  You are saying these two systems are on two separate VLANs.  That means that unless something is passing traffic between the two VLANs, the two devices can't see each other. Even if they are on the same switch, the switch VLAN tagging keeps them separate.  That's why people use VLANs in the first place.

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Michael LPr. SysadminAuthor Commented:
I know the VLANs were created to keep traffic separate, but I'm not sure how they're configured exactly. We have three VLANs; Management, Data, Voice. Our Management and Data VLANs pass traffic between each other, and those VLANs are configured exactly like the Voice VLAN. The Call Manager would be the first device on the Voice VLAN to try to talk to the other two VLANs. I do think the switch's configuration is the culprit, though.
Cliff GaliherCommented:
You'll need to work with your networking team to address that then.
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Windows Server 2016

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