Pls check my previous blog for the Installation , Configuration and Controller Deployment of the NSX 6.1.4 and now we can see how to prepare the esx host and cluster for NSX.

Cluster Installation 

We need to install the NSX bits on all the hosts in the cluster. In the web client go to the Networking & Security – Installation – Host Preparation.

Select the Cluster and click install .

We can see the installation in the recent tasks and the important without putting the ESX in Maintenance Mode the installation will be completed .

In the above PIC we can see the firewall status was unknown which is common and once the process is completed then  we can verify the status of the firewall as enabled.