vCenter vDS Health Check Alarms for VLAN and MTU After Host Power Event

Products

• VMware vCenter Server

Issue/Introduction

ISSUE/INTRODUCTION After a host reboot or an external power event, the following alarms are triggered in the vCenter Server UI:

• vSphere Distributed Switch VLAN trunked status
• vSphere Distributed Switch MTU supported status

Environment

VMware vCenter Server

Cause

The alarms are triggered if the vDS Health Check packets are sent and lost before the ESXi host networking stack has completed initializing or before the upstream switch connection to the host is fully online.

Resolution

1. Acknowledge Alarms in the vCenter UI, acknowledge the affected alarms.
2. Manually reset the alarms to Green.
3. Observe the environment for 5–10 minutes to ensure the alarms do not reappear.
4. If the alarms are triggered again after being cleared on a fully booted host, investigate for a persistent physical network configuration mismatch.

Additional Information

Transient alarms during boot cycles are expected behavior if the physical switch ports do not transition to a forwarding state before the first vDS health probe cycle.

See the following articles for more information on vDS Health Check:

vDS Health Check reports unsupported VLANs for MTU and VLAN

Enabling vSphere Distributed Switch health check in the vSphere Web Client