I came across a situation today while going through an NSX Setup and Configuration where I came across a Cluster under the Host Preparation Tab that was reporting a status of Not Ready – Resolve and listed some hosts as Ready and Not Ready…What made this strange was that this was a fresh deployment of NSX over the top of an existing vCNS Environment.

I decided to investigate at the host level and check to see why the NSX Manager thought these hosts where already prepared with the NSX Host Extensions. I SSH’ed to each host and checked to see if the NSX VIBs where present.

The Hosts marked Ready each had the esx-vxlan and esx-dvfilter-switch-security VIBs installed but not the esx-vsip VIB. The version number got me thinking about the vCNS Implementation of VXLAN and sure enough I found a preconfigured VXLAN Multicast config present by discovering an associated VXLAN, MTU and Teaming Policy set next to the Cluster on the Logical Network Preparation Tab.

My first point of call was to try to uninstall the VIBs on the Hosts and then upon reboot have NSX Manager reinstall the NSX extensions…however all that happened was the previous two VIBs got reinstalled, leaving the esx-vsip VIB still missing…Kind of unexpected…but it appears the ghosts of vCNS remained in play.

With that action failing I decided to move onto uninstalling the old VXLAN config (ensuring no Transport Zones where tied to the Cluster) which removed the references to the old vCNS VXLAN configuration…from there I hit Resolve against the Cluster in the Host Preparation Tab. The Host in the Cluster that was Not Ready had the vCNS Host Extenions installed and took the Installation Status of the Cluster to Legacy with an Option to Update or Uninstall.

Confirming that the previously Not Ready Host only had the vCNS VIBs installed I hit the Update Link and confirmed the Update. The NSX Manager then worked with vCenter DRS to uninstall and then install the updated NSX Host Extensions…along the way putting each host into Maintenance Mode and rebooting for the upgrade to take effect.

One thing I did find is that I had to repeat the process a couple of times for the Updates to go through each host in the Cluster. The process would often do one Host and then require a Retry…not ideal but it got there in the end. I SSH’ed into a couple of the hosts to ensure the right VIBs where now installed.

Biggest take away here is to double check any existing vCNS Environment for Legacy configurations of VXLAN using the old Multicast/vCD method…if not required, make sure the config is removed before the NSX Manager Upgrade.