Before you migrate you must review the documentation, verify that you have the required software versions, modify your existing NSX for vSphere environment if needed, and deploy the infrastructure for the new NSX-T environment.
Check for the latest version of this guide and the release notes for NSX-T Data Center and migration coordinator. You can find the documentation here: https://docs.vmware.com/en/VMware-NSX-T-Data-Center/.
Required Software and Versions
Verify that the NSX for vSphere environment has version 6.4.4.
See the VMware Product Interoperability Matrices for required versions of vCenter Server and ESXi: http://partnerweb.vmware.com/comp_guide2/sim/interop_matrix.php#interop&175=&1=&2=
vSphere Distributed Switch version 6.5.0 and 6.6.0 are supported.
The NSX for vSphere environment must match the NSX-T system requirements for ESXi, vCenter Server, and vSphere Distributed Switch.
If you want to migrate the user roles from NSX for vSphere, you must deploy and configure VMware Identity Manager™. See the VMware Interoperability Matrices for compatible versions: https://www.vmware.com/resources/compatibility/sim/interop_matrix.php#interop&175=&140=. See the VMware Identity Manager documentation for more information.