Network redundancy alerts (NetworkRedundancyLostAlarm) occur across multiple ESXi hosts due to outdated NIC drivers

Products

• VMware vSphere ESXi

Issue/Introduction

VMware vSphere environments may experience intermittent or persistent network redundancy alarms.

Symptoms:

• vCenter Server displays the alarm: Lost uplink redundancy on DVPorts or NetworkRedundancyLostAlarm.
• Multiple hosts in a cluster report the issue simultaneously.
• Physical NICs (vmnics) may flap between UP and DOWN states.

Environment

VMware ESXi 7.x 

VMware ESXi 8.x

Cause

The issue is caused by an unstable or outdated network interface card (NIC) driver. Outdated drivers can fail to correctly manage hardware interrupts or link-state polling, leading to false-positive or intermittent physical link loss even when the upstream switch port remains active.

Resolution

To resolve this issue, the NIC driver must be updated to the latest version validated by the VMware Compatibility Guide (VCG).

1. Log in to the ESXi shell via SSH and run  the below commands to identify current version:
   esxcli network nic get -n vmnicX (Replace X with the affected NIC number).
   
   
2. Note the Driver and Version fields.
   See below for an example output
   Driver Info:
         Bus Info: 0000:04:00:0
         Driver: ixgben
         Firmware Version: 0x80000951, 1.1859.0
         Version: 1.7.1.35
3. Visit the VMware Compatibility Guide and search for your NIC model to find the latest supported asynchronous driver and matching firmware.
4. Download the correct driver VIB or Offline Bundle from Broadcom Support Portal
5. Place the host in Maintenance Mode and run:
   esxcli software vib install -d /path/to/driver-bundle.zip
6. Reboot the host to initialize the new driver.
7. Clear the alarm and monitor the vCenter Events tab to ensure NetworkRedundancyLostAlarm no longer triggers.

Additional Information

If the driver update does not resolve the issue, verify that the physical switch ports are not configured with "Energy Efficient Ethernet" (EEE) or "Green Ethernet," as these features can interfere with link stability on certain NIC models.