Vmware Cloud Foundation duplicate IP addresses issue

Products

• VMware Cloud Foundation

Issue/Introduction

Symptoms:
Hitting issues related to duplicate IP addresses during VCF operations as create VI Domain or Cluster. 
This happens when the environment contains previously removed ESXi Hosts which are not associated to any Cluster.

Environment

VMware Cloud Foundation 4.2.1
VMware Cloud Foundation 4.0.x

Cause

During removal of host operation, the workflow is trying to remove the hosts VMknics and then, it releases the associated IP addresses 
back to the free pool.
However, when there is a failure during removal of VMknics operation and they are not removed successfully, the IP addresses are still released. This behavior could leads to issues. 
For example: when we try to use some IP addresses from the free pool but they are still  associated to the existing hosts.

Resolution

Creating a fix in an upcoming release, that guarantees IP addresses are not released to the free pool during the VCF operation. 
(remove host/cluster/vi, un-stretch cluster) is not able to remove the related VMknics.

Workaround:
Re-image the hosts which are removed from the cluster, so any associated IP addresses are released back and ready to be used again.