Networking is stuck in the past
It wasn’t that long ago when provisioning server resources for an application was manual, time consuming, hardware dependent, error prone, and grossly inefficient. As with many computer science problems, the solution to this inefficiency was automation through softwareabstraction – enabled by server virtualization. The release of VMware ESX paved the way for enterprises to rapidly deploy any application on any server, non-disruptively, by enabling the fundamental abstraction of servers from hardware – creating the virtual machine. Through server virtualization software, application servers are encapsulated into virtual machines, and programmatically deployed with APIs on top generalized pools of CPU and memory resources. The first important step toward the software defined data center.
--> the rest is to be read on the blog : http://blogs.vmware.com/console/2013/03/vmware-nsx-network-virtualization.html