ESXi vmnic link status remains up and redundancy alarms fail to trigger after flap

Products

• VMware vSphere ESX 8.x
• VMware vSphere ESX 7.x

Issue/Introduction

• The link status of the physical network adapter(vmnic) remains up after a flap is observed.
• There are no alarms "network uplink redundancy lost" reported on the respective ESXi host on which a flap is observed for the respective physical network adapter(vmnic).

Environment

VMware vSphere ESX 8.x

Cause

• vCenter Server takes upto 10-second to display the NIC status changes and the "uplink redundancy alarm" on the GUI.

• An event is generated on the specific ESXi host only if the NIC remains in a "down" state for the full 2-second duration.

• If a "NIC UP" signal is received within this 2-second window, no "NIC Down" alarm is triggered.

• This behavior is hardcoded into the vCenter logic and cannot be modified by administrators.

Resolution

This is expected behavior; vCenter will not trigger "uplink redundancy" alarms or report a "NIC down" status if the disconnection lasts less than two seconds.

Additional Information

To understand the cause of the nic down event kindly refer : Network adapter (vmnic) is down or fails with a Failed Criteria Code