Original design
This is the starting point of the infrastructure. A classic design that lot of enterprises have or used to have. Virtual Machine (VM) and Bare Metal Server (BMS) are sharing a same vlan behind a firewall. Everything begins when the VM wants to move to a more virtual infrastructure with distributed routing and firewalling. In this case they want to move to VMware NSXT.
From a physical point of view, the migration is performed on leaf and spine infrastructure that we will call the underlay.