ESXi host loses network connectivity and reverts to nulldev during DVS portset switch

Products

• VMware vSphere ESXi

Issue/Introduction

• Multiple Virtual Machines residing on an ESXi host  become disconnected, resulting in a loss of production network connectivity. An initial reboot of the ESXi host fails to restore VM networking.
• The host attempts a port switch, resulting in the following state change log: DvsPortset-0: changing class from vswitch to cswitch
• The port switch fails and cannot revert to type vswitch, leaving the portset in a nulldev state.

Environment

VMware vSphere ESXI 

VMWare Vcenter  server 

Cause

After the ESXi host reconnects to vCenter, vCenter pushes a DVS configuration via applyDvs. During this process, hostd reads the current version of the DVS by querying the property com.vmware.common.version. This query unexpectedly returns an error, causing the host to fall back and report the version a diffrent version of VDS .

Based on this stale version value, hostd incorrectly enters the isCswitchUpgrade code path. This triggers a hot swap of the portset from vswitch to cswitch. The hot swap fails, and the portset cannot revert to vswitch, leaving it in a disconnected nulldev state.

Resolution

To restore expected network connectivity, perform the following steps to refresh the DVS state on the host:

1. Remove the affected ESXi host from the vSphere Distributed Switch (VDS).

2. Temporarily migrate the management interface (vmk0) to a vSphere Standard Switch (VSS).

3. Re-add the ESXi host to the vSphere Distributed Switch (VDS).

Additional Information

For further guidance on migrating ESXi host networking between standard and distributed switches,

Moving host from DVS to standard switch using ESXi CLI commands

Migrate Virtual Machines (VMs) and VMkernel Adapters from Distributed Switch (vDS) to Standard Switch (vSS)