Learning OpenStack Networking - Third Edition

Visualizing traffic flow through Linux bridges

For an Ethernet frame to travel from a virtual machine instance to a device on the physical network, it will pass through three or four devices inside the host:

Network type	Interface type	Interface name
all	tap	tapN
all	bridge	brqXXXX
vxlan	vxlan	vxlan-z (where Z is the VNI)
vlan	vlan	ethX.Y (where X is the physical interface and Y is the VLAN ID)
flat, vlan	physical	ethX (where X is the interface)

To help conceptualize how Neutron uses Linux bridges, a few examples of Linux bridge architectures are provided in the following sections.