Virtual network
Encyclopedia
A virtual network is a computer network
that consists, at least in part, of virtual network links. A virtual network link is a link that does not consist of a physical (wired or wireless) connection between two computing devices but is implemented using methods of network virtualization
.
The two most common forms of virtual networks are protocol-based virtual networks (such as VLAN
s, VPN
s, and VPLS
s) and virtual networks that are based on virtual devices (such as the networks connecting virtual machine
s inside a hypervisor
). In practice, both forms can be used in conjunction.
VLANs (Virtual LANs) are logical LAN
's (Local Area Networks), based on physical LAN's. A VLAN can be created by partitioning a physical LAN into multiple logical LAN's (subnets) using a VLAN ID. Alternatively, several physical LAN's can function as a single logical LAN. The partitioned network can be on a single router, or multiple VLAN's can be on multiple routers just as multiple physical LAN's would be. A VLAN can be on a VPN.
A VPN (Virtual Private Network
) consists of multiple remote end-points (typically routers, VPN gateways of software clients) joined by some sort of tunnel over another network, usually a third party network. Two such end points constitute a 'Point to Point Virtual Private Network' (or a PTP VPN). Connecting more than two end points by putting in place a mesh of tunnels creates a 'Multipoint VPN'.
A VPLS (Virtual Private LAN Service) is a specific type of Multipoint VPN. VPLS are divided into Transparent LAN Services (TLS) and Ethernet Virtual Connection Services. A TLS sends what it receives, so it provides geographic separation, but not VLAN subnetting. An EVCS adds a VLAN ID, so it provides geographic separation and VLAN subnetting.
A common example of a virtual network that is based on virtual devices is the network inside a VMware ESX virtual host that is implemented using virtual switches (vSwitches). Such networks can use non-virtual protocols such as Ethernet as well as virtualization protocols such as the VLAN protocol IEEE 802.1Q
.
Computer network
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
that consists, at least in part, of virtual network links. A virtual network link is a link that does not consist of a physical (wired or wireless) connection between two computing devices but is implemented using methods of network virtualization
Network virtualization
In computing, Network Virtualization is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network...
.
The two most common forms of virtual networks are protocol-based virtual networks (such as VLAN
Virtual LAN
A virtual local area network, virtual LAN or VLAN, is a group of hosts with a common set of requirements that communicate as if they were attached to the same broadcast domain, regardless of their physical location...
s, VPN
Virtual private network
A virtual private network is a network that uses primarily public telecommunication infrastructure, such as the Internet, to provide remote offices or traveling users access to a central organizational network....
s, and VPLS
Virtual Private LAN Service
Virtual Private LAN Service is a way to provide Ethernet based multipoint to multipoint communication over IP/MPLS networks. It allows geographically dispersed sites to share an Ethernet broadcast domain by connecting sites through pseudo-wires. The technologies that can be used as pseudo-wire can...
s) and virtual networks that are based on virtual devices (such as the networks connecting virtual machine
Virtual machine
A virtual machine is a "completely isolated guest operating system installation within a normal host operating system". Modern virtual machines are implemented with either software emulation or hardware virtualization or both together.-VM Definitions:A virtual machine is a software...
s inside a hypervisor
Hypervisor
In computing, a hypervisor, also called virtual machine manager , is one of many hardware virtualization techniques that allow multiple operating systems, termed guests, to run concurrently on a host computer. It is so named because it is conceptually one level higher than a supervisory program...
). In practice, both forms can be used in conjunction.
VLANs (Virtual LANs) are logical LAN
Län
Län and lääni refer to the administrative divisions used in Sweden and previously in Finland. The provinces of Finland were abolished on January 1, 2010....
's (Local Area Networks), based on physical LAN's. A VLAN can be created by partitioning a physical LAN into multiple logical LAN's (subnets) using a VLAN ID. Alternatively, several physical LAN's can function as a single logical LAN. The partitioned network can be on a single router, or multiple VLAN's can be on multiple routers just as multiple physical LAN's would be. A VLAN can be on a VPN.
A VPN (Virtual Private Network
Virtual private network
A virtual private network is a network that uses primarily public telecommunication infrastructure, such as the Internet, to provide remote offices or traveling users access to a central organizational network....
) consists of multiple remote end-points (typically routers, VPN gateways of software clients) joined by some sort of tunnel over another network, usually a third party network. Two such end points constitute a 'Point to Point Virtual Private Network' (or a PTP VPN). Connecting more than two end points by putting in place a mesh of tunnels creates a 'Multipoint VPN'.
A VPLS (Virtual Private LAN Service) is a specific type of Multipoint VPN. VPLS are divided into Transparent LAN Services (TLS) and Ethernet Virtual Connection Services. A TLS sends what it receives, so it provides geographic separation, but not VLAN subnetting. An EVCS adds a VLAN ID, so it provides geographic separation and VLAN subnetting.
A common example of a virtual network that is based on virtual devices is the network inside a VMware ESX virtual host that is implemented using virtual switches (vSwitches). Such networks can use non-virtual protocols such as Ethernet as well as virtualization protocols such as the VLAN protocol IEEE 802.1Q
IEEE 802.1Q
IEEE 802.1Q is the networking standard that supports Virtual LANs on an Ethernet network. The standard defines a system of VLAN tagging for Ethernet frames and the accompanying procedures to be used by bridges and switches in handling such frames...
.
See also
- Overlay NetworkOverlay networkAn overlay network is a computer network which is built on the top of another network. Nodes in the overlay can be thought of as being connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network...
- Network VirtualizationNetwork virtualizationIn computing, Network Virtualization is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network...
- Virtual CircuitVirtual circuitIn telecommunications and computer networks, a virtual circuit , synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication...
- Virtual MachineVirtual machineA virtual machine is a "completely isolated guest operating system installation within a normal host operating system". Modern virtual machines are implemented with either software emulation or hardware virtualization or both together.-VM Definitions:A virtual machine is a software...