Azure Nested VM pinging issue

Question

Hi

I have created VM on Azure with Windows Server 2019. Hyper-V is installed on this VM. I have created Internal NAT switch and 1 VM on the Hyper-V.

IP Setting on Hyper-V is below.

10.0.0.4 (assigned by Azure Vnet)

192.168.0.1 (Internal NAT Switch IP)

DHCP is install on the hyper-v (Assigning IP to inside the hyper-v VM)

VM inside the virtual machine and hypervisor itself both are pinging to each other

What is issue?

I have created one more subnet on the Azure VNET and then created one more azure VM. New subnet is attached with this new VM.

This new VM is not pinging to Hyper-V switch (192.168.0.1) and inside hyper-v VM. It is only pinging to 10.0.0.4 (Hyper v IP which is assigned by Azure Vnet) But Hyper-V server and inside the vm both are pinging to this new Azure VM.

Firewall is off on all VMs

Please any tip?

Regards

Answer 1

Hi, Your new VM in Azure is not aware of the 192.x.x.x ip space. You will need to create a Route table and forward the traffic to 10.x.x.x ip and once the packet reaches the destination Azure VM, you will need to perform DNAT based on the port and forward it to right VM.

Answer 2

Hi,

Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.

I understand that you would like to use Nested Virtualization in Azure.

You are not able to ping the IP of the HyperV Switch nor the NestedVM's IP.

This is an expected behavior.

While Azure Supports Nested Virtualization for certain VM sizes, the underlying Azure Platform will not be aware of the IPs used by the HyperV switch and the NestedVM.

In other words, the NestedVM will NOT be part of the Azure Vnet

For a traffic destined to a NestedVM

• You have to use the IP of the VM (Azure Provided) to route traffic to the AzureVM
• And within Azure VM, you have to NAT it to the IP of the NestedVM
• Refer : Networking for Nested Virtualization

Please let us know if you require further information on this.

Cheers,

Kapi