No alarm triggered when vmnic is down

Products

• VMware vSphere ESX 8.x

Issue/Introduction

• The vmnic is configured as an Active adapters  or as a Standby adapters on a virtual switch.
• No VMkernel adapter (vmk) or powered-on virtual machines are associated with the vmnic. 
• No alarms such as Network connectivity lost or Network uplink redundancy lost are triggered when the vmnic link goes down.

Environment

VMware vCenter Server 8.x

VMware vSphere ESXi 8.x

Cause

This behavior is expected. No alarms will be generated if no active virtual machines or vmks are associated with the vmnic.

Resolution

If an alarm needs to be triggered for this situation, a custom alarm definition can be created in vCenter Server.

To configure the alarm:

1. Log in to the vCenter Server web client.

2. Navigate to vCenter instance > Configure > Alarm Definitions > Add.

3. On the Name and Targets page:

   • Enter the alarm name in the Alarm Name field.

   • Select Hosts from the Target type drop-down menu.

   • Click Next.

4. On the Alarm rule 1 page:

   • Under Select a trigger, choose Link state down.

   • Under Select severity, select the desired severity level.

   • Optionally enable Send email notifications, Send SNMP traps, or Run script as required.

   • Click Next.

5. On the Reset Rule 1 page:

   • Enable Reset the alarm to green if a reset condition and action are needed.

   • Click Next.

6. Review the configuration summary and click Create to complete the alarm setup.