• During a Live Migration, the system loses its network configuration. After reboot, the VM does not function until the IP address, subnet mask, gateway, and DNS are manually reconfigured.
• Live Migration refers to moving a virtual machine from one Hyper-V host to another, similar to VMware vMotion.
• Investigation showed that the Linux network configuration under /etc/sysconfig/network/ detected new Ethernet interfaces after migration. A reboot was required, and the system then displayed a setup menu prompting for IP address and hostname configuration, similar to the initial installation process.
• After reconfiguration, the network settings were restored and the Ethernet interfaces were correctly displayed with their details.

The Hyper-V virtual machine is configured with a dynamic MAC address on the Ethernet network interface. As a result, the MAC address changes after a reboot or Live Migration.

Since the Linux operating system associates network configuration (including IP settings) with the system’s MAC address, the change causes the VM to lose its existing network configuration, resulting in loss of IP settings.

To resolve this issue, perform the following steps:

1. Power off the Hyper-V virtual machine.
2. Open the Hyper-V Virtual Machine Settings.
3. Navigate to the network adapter (Ethernet NIC) configuration.
4. Assign a Static MAC Address to the network adapter.

Unlike most network configuration changes, the MAC address must be set while the virtual machine is powered off.

Verification

• Start the Hyper-V virtual machine.
• Confirm that the network configuration (IP address, subnet mask, gateway, and DNS) remains intact after reboot or Live Migration.
• Verify that the system no longer prompts for initial network setup.
• Check that network connectivity is restored and stable (e.g., ping gateway/DNS or access external/internal resources).