Chapter 17. Virtual Networking

Libvirt virtual networking uses the concept of a virtual network switch. A virtual network switch is a software construct that operates on a host physical machine server, to which virtual machines (guests) connect. The network traffic for a guest is directed through this switch:

Linux host physical machine servers represent a virtual network switch as a network interface. When the libvirtd daemon (libvirtd) is first installed and started, the default network interface representing the virtual network switch is virbr0.

This virbr0 interface can be viewed with the ip command like any other interface:

ip addr show virbr0

 $ ip addr show virbr0
 3: virbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN
     link/ether 1b:c4:94:cf:fd:17 brd ff:ff:ff:ff:ff:ff
     inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0