Network virtualization is a term for very different approaches at hardware and software level to combine network resources into logical units or to divide them up, which are - relatively - independent of the physical conditions. This often involves the implementation of sophisticated security concepts.
A common example of this is Virtual Private Networks( VPN), which create a logical communication link between two participants or two computers that uses strong encryption, creating a virtual "tunnel" for the parties through which communication can take place. Another example is software defined networking( SDN).
Network virtualization, for example, adds a logical - virtual - layer to a local area network( LAN) that decouples the user or communications client from physical realities. Both the complexity and heterogeneity of the devices are concealed in order to ensure a uniform view and administration. For reasons of better overview, administrability and higher flexibility, physical networks are divided into logical subunits by means of suitable technologies - virtualizing switches, routers, etc. - on the one hand, and on the other hand, these can also be combined into larger units across locations - depending on requirements and tasks.
Virtual Local Area Networks ( VLAN), for example, ensure flexible shared use of local networks (LAN). Here, many different defined network connections can be switched in parallel via a physical LAN. These are virtually separated from each other, so that devices in one VLAN cannot communicate with or even "see" devices in other VLANs. From the subscribers ' point of view, the VLAN behaves like a physical LAN. Depending on the technology used, VLANs can be implemented on one of the layers from 1 to 4 of the OSI protocol. This approach increases security, creates additional logical units, and generally requires significantly fewer technical components compared to implementation as different physical networks.