Learning OpenStack Networking - Third Edition

Bridge mappings

The bridge_mappings configuration option describes the mapping of an artificial label to a virtual switch created with Open vSwitch. Unlike the Linux bridge driver that configures a separate bridge for every network, each with its own interface, the Open vSwitch driver uses a single virtual switch containing a single physical interface and uses flow rules to tag traffic if necessary.

When networks are created, they are associated with an interface label, such as physnet1. The label physnet1 is then mapped to a bridge, such as br-eth1, which contains the physical interface eth1. The mapping of the label to the bridge interface is handled by the bridge_mappings option. This mapping can be observed as follows:

bridge_mappings ...