Visualizing the traffic flow when using Open vSwitch

When using the Open vSwitch driver, for an Ethernet frame to travel from the virtual machine instance out through the physical server interface, it will potentially pass through nine devices inside the host:

• The tap interface: tapXXXX

• The Linux bridge: qbrXXXX

• The veth pair: qvbXXXX, qvoXXXX

• The OVS integration bridge: br-int

• OVS patch ports: int-br-ethX and phy-br-ethX

• The OVS provider bridge: br-ethX

• The physical interface: ethX

• The OVS tunnel bridge: br-tun

The Open vSwitch bridge br-int is known as the integration bridge. The integration bridge is the central virtual switch that most virtual devices are connected to, including instances, DHCP servers, routers, and more. When Neutron security groups are enabled, however, instances are not directly connected to the integration bridge. Instead, instances are connected to individual Linux bridges that are cross connected to the integration bridge using a veth cable.

Note

The reliance on Linux bridges...