Error Node with same ip already exists when preparing ESXi for NSX

Products

• VMware NSX

Issue/Introduction

• ESXi host is being prepared for NSX.
• ESXi may, or may not be deployed in VxRail cluster (configuration outlined below is typical for VxRail deployment). 
• Host is using two vmknics for management.
• First management vmknic is set with a static IPv4 IP address.
• IPv4 on the first management vmknic is already used on another host prepared for NSX. 
• When adding a new host, the following error is observed:
  Error: Node example-esxi.local with same ip <IP address of host example-esxi.local>  already exists. Check the state of existing transport node. If it is a failure in deletion then use force option to delete previous transport node and retry the operation. If the host is part of a cluster having transport node profile applied then then move the host into datacenter before deletion. Refer KB article number 319975 for more details. (Error code: 26210)

Environment

• VMware NSX
• VMware NSX-T Data Center

Cause

• Same static IPv4 IP address was configured on different ESXi host's vmk0 interfaces.
• This can be observed in VxRail environments, as VxRail will use two management vmknics:
  • the first, usually vmk0 will only be using IPv6, IPv4 should not be set. This vmknic is used for internal management within VxRail. 
  • the second vmknic is usually used for management of the ESXi host (e.g. connection of the host to the vCenter, SSH connectivity to the host, etc.).

Resolution

• If you configured a static IPv4 IP address on the first management vmknic (usually vmk0), ensure this IPv4 address is not used by any other ESXi host in the cluster. 

Additional Information

Please also see KB article Installing or Upgrading NSX on an ESXi host fails reporting the node already exists for error "Node <node-name> with same ip <###.###.###.###> already exists".