virtual networking devices

There are four distinct type of virtual networking devices: TAP devices, veth
pairs, Linux bridges, and Open vSwitch bridges. For an Ethernet frame to travel
from eth0 of virtual machine vm01 to the physical network, it must pass
through nine devices inside of the host: TAP vnet0, Linux bridge qbrNNN, veth
pair (qvbNNN, qvoNNN), Open vSwitch bridge br-int, veth pair (intbr-
eth1, phy-br-eth1), and, finally, the physical network interface card
eth1.

- qvo: veth pair openvswitch side

- qvb: veth pair bridge side

- qbr: bridge

- qr: l3 agent managed port, router side

- qg: l3 agent managed port, gateway side