vMotion VMkernel connectivity fails between ESXi hosts

Products

• VMware vSphere ESXi

Issue/Introduction

• ESXi hosts are unable to communicate over the vMotion VMkernel network.
• The affected environment uses Cisco UCS X-Series, with ESXi physical NICs connected through separate UCS fabrics:
  • vmnic0 connected through Fabric A
  • vmnic1 connected through Fabric B
• VMkernel adapters on different ESXi hosts may be associated with physical NICs connected through different UCS fabrics.
• Connectivity may work between some ESXi hosts while failing between others.

Environment

VMware vSphere ESXI 8.x

Cause

The VLAN used by the vMotion VMkernel network is not configured or allowed on one of the upstream network port-channels used by the ESXi host uplinks.

Resolution

Ensure that the VLAN used by the vMotion VMkernel network is configured and allowed on all applicable upstream switch ports and port-channels associated with both UCS fabrics.

After correcting the upstream VLAN configuration, verify connectivity between the vMotion VMkernel adapters:

vmkping -I vmkX <destination_vMotion_IP>

For additional troubleshooting steps see the following KB: Testing VMkernel network connectivity with the vmkping command