In a close analogy to the virtual machine, a virtualized network is a software container that presents logical network components—logical switches, routers, firewalls, load balancers, VPNs and more—to connected workloads.
These virtualized networks are programmatically created, provisioned and managed, with the underlying physical network serving as a simple packet-forwarding backplane. Network and security services are allocated to each VM according to its needs, and stay attached to it as the VM moves among hosts in the dynamic virtualized environment.