Azure Virtual Machines
An Azure service that is used to provision Windows and Linux virtual machines.
7,588 questions
Nested Hyper-V VMs running on Azure VMs (hosts) in EAST US and EAST US 2 can't communicate directly with each other.
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Clark Warren
0
Reputation points
The nested Hyper-V VMs can ping the Azure VMs (hosts) across my peered VNETs in both directions, but they cannot ping each other directly. The nested Hyper-V VMs are attached to internal virtual NAT switches per MS documentation, so traffic goes out from them correctly to other end points inside the two VNETs, but inbound traffic is not making it past the Azure VM (host) to the Hyper-V VM running on it.
What is required to make the nested Hyper-V VMs communicate directly with each other successfully in this scenario?
{count} votes
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Andreas Baumgarten 104K Reputation points MVP2024-07-05T16:45:27.17+00:00 Hi @Clark Warren ,
are you able to ping from host in vNet (East US) to host in vNet (East US 2)? Just to verify the routing and peering is working in general.
(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Regards
Andreas Baumgarten
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Clark Warren 0 Reputation points
2024-07-05T16:57:09.9733333+00:00
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Clark Warren 0 Reputation points
2024-07-05T17:29:08.2966667+00:00 Andreas,
Yes, I can ping from Azure VM (host) in East US to Azure VM (host) in East US 2 and vice versa. I cannot ping between the Hyper-V Nested VMs running on each Azure VM (host).
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Clark Warren 0 Reputation points
2024-07-05T17:29:32.9733333+00:00 Andreas,
Yes, I can ping successfully as follows:
Azure VM (host) East US to Azure VM (host) East US 2 and vice versa.
Nested Hyper-V VM East US to both Azure VM (hosts).
Nested Hyper-V VM East US 2 to both Azure VM (hosts).
What I cannot ping successfully is as follows:
Azure VM (host) East US to Nested Hyper-V VM East US 2.
Azure VM (host) East US 2 to Nested Hyper-V VM East US.
Nested Hyper-V VM East US to Nested Hyper-V VM East US 2 and vice versa.
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Nikhil Duserla 1,300 Reputation points Microsoft Vendor2024-07-11T06:06:11.4+00:00 Hi Clark Warren ,
Thank you for providing information.
The issue you're facing is due to the fact that the Azure VMs (hosts) are not routing traffic between the nested Hyper-V VMs. This is because the Azure VMs are not configured to route traffic between the two subnets.
Enable IP Forwarding on the Azure VMs.
Configure Routes on the Azure VMs.
Verify that firewall rules on the Azure VMs (hosts) permit traffic forwarding between the two subnets.
If you are still facing issue. I suggest filing a support case to investigate this matter further. The support team will be able to examine and assist with resolving the issue.
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Nikhil Duserla 1,300 Reputation points Microsoft Vendor
2024-07-12T05:54:21.57+00:00 Hi Clark Warren ,
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
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Clark Warren 0 Reputation points
2024-07-12T13:36:14.9266667+00:00 Nikhil,
Yes, I have tried all of the above and a few other things not listed above as well. The Azure VM Host either can't forward the traffic to the Internal NAT Switch (required and set up via MS documentation) OR the Internal NAT Switch can't accept the traffic it is receiving from the Azure VM Host. Either way any traffic coming from outside the VNET the nested Hyper-V VM resides in can't reach the nested Hyper-V VM.
When you say, "Verify that firewall rules on the Azure VMs (hosts) permit traffic forwarding between the two subnets." can you please be more specific. Maybe there is something I haven't tried in this regard, but I don't know what that would be.
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Nikhil Duserla 1,300 Reputation points Microsoft Vendor
2024-07-17T06:05:23.5366667+00:00 Hi Clark Warren,
Thank you for providing information. I suggest filing a support case to investigate this matter further. The support team will be able to examine and assist with resolving the issue.
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Clark Warren 0 Reputation points
2024-07-17T16:10:30.2733333+00:00 Nikhil,
Yeah, I did that over three weeks ago and still no resolution yet from Microsoft Support. When I figure out how to make this work I will post the results, so anyone else running into this can replicate the solution. I can't be the only person who needs this to work correctly.
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