Open vSwitch (OVS) is an open source OpenFlow capable virtual switch that is typically used with hypervisors to interconnect virtual machines within a host and between different hosts across networks. Overlay networks need to create a virtual data path using supported tunneling encapsulations, such as VXLAN or GRE.

The overlay data path is provisioned between tunnel endpoints residing in the Docker host that gives the appearance of all hosts within a given provider segment being directly connected to one another.

As a new container comes online, the prefix is updated in the routing protocol announcing its location via a tunnel endpoint. As the other Docker hosts receive the updates, the forwarding is installed into OVS for which tunnel endpoint the host resides. When the host is deprovisioned, a similar process occurs and tunnel endpoint Docker hosts remove the forwarding entry for the deprovisioned container:

Communication between containers...