When adding a previously provisioned ESXi host to a cluster in VMware NSX for vSphere 6.1.x, the cluster status for VXLAN displays an error: Error Unconfigure

Products

• VMware NSX for vSphere

Issue/Introduction

Symptoms:

• When Navigating to Networking and Security > Installation > Host Preparation, you see that a cluster under VXLAN reports Error Unconfigure even when all ESXi hosts are reported as Ready under the installation status.
• Clicking the error icon reports the error :
  VTEP has not been created successfully on the Host.
  
• Adding an ESXi host to the cluster reports multiple entries in the task list for task(s) similar to:
  "Add virtual NIC": An error occurred during host configuration.
  
• NSX VIBs are correctly installed on the affected ESXi host that is configured with a VTEP vmkernel interface.
• Rebooting the affected ESXi host does not resolve the issue.
• There are adequate free IP addresses in the IP Pool assigned to the cluster under Networking and Security > Installation > Logical Network Preparation > VXLAN Transport: VMKNic IP Addressing.

Environment

VMware NSX for vSphere 6.1.x

Cause

An ESXi host that had been previously prepared for NSX was removed from the NSX cluster, and then added back to an NSX-prepared cluster (or different cluster) triggering a host preparation activity. When the ESXi host was removed initially, it should have triggered an un-prepare action. However, the un-prepare did not complete successfully, the host was not rebooted to complete the un-preparation, and /or the VXLAN Tunnel End Point (VTEP vmkernel interface removal failed, which causes the host preparation task to fail when trying to re-create the VTEP as it already exist.

Resolution

To resolve this issue, after removing the ESXi host from an NSX-prepared cluster, ensure that the VTEP vmkernel interface is removed before attempting to add it back into an NSX-prepared cluster.

To manually remove the VTEP vmkernel interface on the ESXi host:

1. Put the ESXi host into maintenance mode
2. Remove the ESXi host from the NSX prepared cluster.
3. Reboot the host
4. If the VTEP vmkernel interface is still present on the ESXi host after the reboot, manually delete it from the host networking VMkernel interface configuration.
5. Re-add the ESXi host to the NSX prepared cluster and allow it to be prepared.

Additional Information