Virtual Area NetworkThe Virtual Area Network or VAN is a virtual LAN which runs on top on a physical LAN. Virtual nodes can communicate over the VAN without the ability to interact with the physical LAN. This enables guest virtual machines on seperate physical hosts to communicate. The packets travel over the connecting LAN but are unable to reach any physical device on the network. Each physical node in the VAN is configured with a virtual TAP ethernet adapter. This interface is then bridged with the virtual machine interface. A daemon/service then takes packets from the TAP, encapsulates them in the VAN protocol and sends then over the physical LAN. The daemon/service also takes and VAN packets from the LAN, strips the VAN protocol headers and injects the packed into the TAP. Currently the VAN protocol is very simple but does allow for a full 1500 byte MTU to be sent over the LAN by spliting it up into two packets. LAN communication is done via UDP broadcast or multicast. Although not exact, this gives simalar performance to a real ethernet LAN. The VAN header also has a Virtual network ID or VNET which allows multiple VANs to operate on the same LAN or multicast group. No security is provided in the VAN protocol. The VAN was developed for VMWare clients but some success has also been had with VPC. A few workarounds are required but hopefuly MS will respond to the pressure exerted by VMware and fix the bugs Although designed for virtual machines, the VAN can also be used nativly which allows a combination of physical and virtual nodes on the virtual network. This has been used to allow interaction with physical hardware such as Cisco routers and with Linux to route packets to and from the physical network This software will be available soon for both Windows and Linux under the GPL License Version 2.
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