NetworkRedundancyLostAlarm on ESXi hosts when Hardware-Assisted Virtualization is enabled

Products

• VMware vSphere ESXi

Issue/Introduction

In a VMware vCenter environment, ESXi hosts may trigger a critical NetworkRedundancyLostAlarm. This issue occurs specifically when virtual machines (VMs) residing on the host have hardware-assisted virtualization enabled.

You will observe the following symptoms:

• Critical alarms in vCenter logs:

  [Critical] Alarm alarm.NetworkRedundancyLostAlarm on Host <hostname> because Lost uplink redundancy on virtual switch "vSwitch0". Physical NIC vmnic1 is down.

• The physical NIC (e.g., vmnic1) is reported as down, coinciding with the activation of hardware virtualization features on resident VMs.

Environment

VMware ESXi

Cause

The underlying root cause for why hardware virtualization triggers a physical NIC down state is currently not fully identified. However, a direct correlation exists between enabling hardware-assisted virtualization on VMs and the loss of network redundancy on the host.

Resolution

NOTE: For environments with this condition, proceed to gather a support bundle and open a Networking Support Case with Broadcom Support.  Use the instructions in the following document for Creating and managing Broadcom support cases.

As a workaround, you must disable hardware-assisted virtualization on the impacted virtual machines to restore network stability and uplink redundancy.

1. Power off the affected virtual machine.
2. Right-click the VM in the vCenter inventory and select Edit Settings.
3. Navigate to the VM Options tab.
4. Expand CPUID Mask or Expose hardware assisted virtualization to the guest OS (depending on your vSphere version).
5. Deselect/Disable the option for hardware-assisted virtualization.
6. Click OK and power on the VM.