One of the goals of the SDN Testing is to test SDN concepts such as the Virtual Datacenter Replacement. A True Virtual Data Center consists of a few pieces:
A software based router with the ability to connect multiple uplinks and use a routing protocol to load-balance between them.
A software based switch with industry standard features and a good control interface.
A software based firewall with the ability to separate the front and backend systems safely.
The front and back-end systems themselves.