Virtual network device services are provided by shared memory
communication with a backend domain. From the point of view of other
domains, the backend may be viewed as a virtual ethernet switch
element with each domain having one or more virtual network interfaces
connected to it.
From the point of view of the backend domain itself, the network
backend driver consists of a number of ethernet devices. Each of
these has a logical direct connection to a virtual network device in
another domain. This allows the backend domain to route, bridge,
firewall, etc the traffic to / from the other domains using normal
operating system mechanisms.