Visualizing traffic flow when using LinuxBridge

While an Ethernet frame travels from the virtual machine instance to a remote physical network, it passes through three or four of the following devices depending on the network type:

• The tap interface: tapN

• The Linux bridge: brqXXXX

• The VXLAN interface: vxlan-Z (where z is the VNI)

• The VLAN interface: ethX.Y (where X is the interface and Y is the VLAN ID)

• The physical interface: ethX (where X is the interface)

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

VLAN

Imagine a basic OpenStack cloud that consists of a single network on VLAN 100 for use with instances. The network architecture within the compute node resembles the following:

Figure 4.6

In Figure 4.6, three virtual machine instances are connected to a Linux bridge named brqXXXX via their respective tap interfaces. When an instance was launched in the network mapped to VLAN 100, a virtual interface named...