A virtual network is a network that emulates a physical network and is a combination of hardware and software network resources. A virtual network is the end product of network virtualization.
Virtual networks are classified into two broad types: external and internal.
External virtual networks consist of several local networks that are administered by software as a single entity. The building blocks of classic external virtual networks are switch hardware and virtual local area network (VLAN) software technology. Examples of external virtual networks include large corporate networks and data centers. For more information about VLANs, see Chapter 3, Configuring Virtual Networks by Using Virtual Local Area Networks, in Managing Network Datalinks in Oracle Solaris 11.2 .
Internal virtual networks consist of one system using virtual machines or zones whose network interfaces are configured over at least one physical network interface card (NIC). Those network interfaces are called virtual network interface cards or virtual NICs (VNICs). These virtual machines or zones can communicate with each other as though they were on the same local network, effectively becoming a virtual network on a single host. The chapters in this document focus on the internal virtual network.
A special type of internal virtual network is the private virtual network. Private virtual networks are different from virtual private networks (VPNs). VPN creates a secure point-to-point link between two endpoint systems. The private virtual network is a virtual network on a system that cannot be accessed by external networks. The isolation of this internal network from other external networks is achieved by configuring VNICs over a pseudo NIC called an etherstub. For more information, see Etherstub.